Capabilities
Compare Free, Pro, and Pro+ features, plus how Storm Window treats each forecast risk factor.
Storm Window keeps the safety core available to every user. Pro adds best-time planning, personalization, multiple places, full trend charts, and deeper inspection. Pro+ adds expanded monitored locations, flexible Plans with forecast-trend monitoring, proactive monitoring, forecast-change alerts, advanced planning layers, and AI-backed explanations. Focused Lightning and Wind maps add nearby context without changing the risk engine. Forecast values stay unchanged; profiles and personal settings tune how risk is classified for the selected activity. Saved locations, custom profiles, and key settings sync automatically across devices on the same Apple ID.
Feature tiers
Free answers whether it is safe. Pro plans your best window today and personalizes the forecast. Pro+ plans ahead across days and watches for meaningful changes. AI-generated guidance is one Pro+ explanation path, but Pro+ features continue to work with Storm Window’s deterministic fallback when AI is unavailable or turned off.
| Capability | Free | Pro | Pro+ |
|---|---|---|---|
| Low-risk window verdict — the headline that answers “when is it safe to go out?” Shows the current window status (Low risk / Caution / Unsafe / Dangerous), when the window closes, and when the next window opens, backed by a swipeable 3-day risk chart with a lowest-risk window summary. NWS alert overlay appears only when official guidance is more cautious than the matching local model data | Included | Included | Included |
| Factors & Conditions trend charts — an expandable panel below the risk chart with hourly line/area graphs over the same day. Factors graphs whichever signals are actively driving or explaining the current rating — Wind (speed/gusts with directional arrows), Heat, Storms, Air Quality, Marine and Cold Water (water activities only), and Alerts — showing only the ones with relevant data and prioritizing active risk drivers. Conditions graphs informational Precipitation, Temperature, Sky, UV, and Comfort trends that never change the verdict. Free can switch modes and swipe chart pages in preview; paired-line pages keep both lines visible while highlighting the focused metric. Pro unlocks full chart inspection | Interactive preview | Included | Included |
| Core safety inputs — the factors that can close a low-risk window: lightning, thunderstorms, heat index, estimated heat stress (WBGT-like), AQI, dangerous wind gusts, wind chill, flood risk, marine wave height, cold-water exposure for relevant water activities, and active NWS alerts | Included | Included | Included |
| Planning context — informational overlays that add texture without changing the verdict: current sky condition (clear, partly cloudy, etc.), optional rain/snow overlay, UV index advisory, altitude advisory for mountain activities above ~5,000 ft, air temperature, and a basic per-hour explanation of the rating | Included | Included | Included |
| Focused safety maps — native Lightning Map and Wind Map surfaces opened from the Maps tab or Home risk pill when map context is available. Lightning Map shows recent radar, NOAA lightning activity density, Storm Window live-lightning context, distance rings, and a short radar-motion scrubber with playback controls. Wind Map shows forward-looking NOAA/NWS wind speed, gust, optional radar context, sparse native direction arrows, and, for Pro users in the supported contiguous-U.S. HRRR coverage area, animated Flow particles driven by backend NOAA HRRR U/V wind vectors. NOAA map context is informational only; Storm Window’s point forecast and activity thresholds remain authoritative for the verdict | Included | Included | Included |
| Siri, Shortcuts & Control Center — ask Siri or run a Shortcut for the current safety verdict, the next safe window, or the risk at a saved location, and add Home Screen/Lock Screen Control Center buttons for current risk, next safe window, and starting an outdoor session. Pro adds a duration-aware “best time to go” Shortcut and Siri phrase; Pro+ adds a Plan-status Shortcut and Siri phrase | Included | Included | Included |
| Widgets and complications — active-location Home Screen widgets (small, medium, and large), Lock Screen widgets, Apple Watch app, and default watch complications that follow the Watch app’s current location and activity. Compact charts use the same hourly risk categories as the app | Included | Included | Included |
| Imminent hazard alert — an on-device local notification scheduled from the cached forecast, warning when dangerous conditions are approaching the active location within the next couple of hours | Included | Included | Included |
| iCloud sync — saved locations (including renames and deletes), custom activity profiles, activity profile selection, personal profile settings, and the Cautious Lightning toggle sync automatically across devices on the same Apple ID; notification settings and display preferences remain per-device | Included | Included | Included |
| Storm Window Updates — opt in to Tips & Safety Information and New Features & Announcements push messages sent occasionally by SiPhy | Included | Included | Included |
| Pro+ proactive monitoring alerts — window-change, best-window-starting, next-window-changed, daily briefing, and Plan forecast changed alerts for near-term conditions and future Plans. These are device-scheduled from cached forecasts unless a backend delivery path is explicitly enabled for that alert category. Safety category toggles (Lightning, Heat, Air Quality, High Wind, Severe Weather) tune backend safety-alert paths when available | Not included | Not included | Included |
| Saved locations — places you return to, beyond Follow My Location (included free on every plan and never counted against this limit); Free supports 1 additional pinned place, Pro expands to ten, and Pro+ supports up to twenty-five for planning-heavy users. Adding a location stores it for fast switching without re-entering an address; each location caches its own forecast for offline viewing | Follow My Location + 1 | Follow My Location + 10 | Follow My Location + 25 |
| Watch multiple activities per location — a single saved place can matter for more than one activity, such as golf and swimming at the same lake house. Storm Window keeps a separate verdict for each watched activity and shows a chip strip on Home to switch between them without changing your default activity; a single approaching hazard produces one notification naming every affected activity, not one per activity | Up to 2 | Up to 5 | Unlimited |
| Best Time Today — the best low-risk window for your activity, sized to how long you plan to be out, graded Excellent to Poor with a quality score. Includes start-by guidance (the latest time to begin and still finish before conditions turn), a next-best alternative window, and a deterministic reason when the window ends. Preferred-hours settings keep the suggestion practical (daytime by default) unless you allow overnight windows | Not included | Included | Included |
| Activity comparison — for the selected hour, see how the current conditions rate for a representative set of activities, grouped into Good, Use Caution, and Avoid. Tap an activity you’re not already watching to add it as a watched activity at the current location (subject to that tier’s per-location limit); anything already watched before the panel was opened stays locked so it can’t be removed by accident | Not included | Included | Included |
| Outdoor Session Live Activity — start a weather-exposure session for the selected activity and place from the Best Time Today card; a Live Activity keeps showing current risk, remaining usable time, and the next change on the Lock Screen or Dynamic Island, with supported controls to extend by 15 minutes or end the shared session | Not included | Included | Included |
| Location nicknames — rename any saved place to a short, personal label (“Home,” “Track,” “Lake House”) that appears throughout the app, widgets, and complications | Not included | Included | Included |
| Core activity profiles: Everyday, Walker, Runner, Cyclist, Stroller, and Using a Baby Carrier — each with appropriate wind, heat, and lightning thresholds for the activity | Included | Included | Included |
| Chart style — choose Bars or Dots for the daily risk pager and compact charts in widgets, the Watch app, and rectangular complications. Bars show relative severity; Dots show hourly risk categories as compact capsules | Included | Included | Included |
| Extended built-in profiles — 15+ additional profiles for Hiker, Climber, Golfer, Tennis/Pickleball, Beach, Pool & Swim, Open Water Swim, Small Boat, Sailboat, Powerboat, Offshore Boat, Paddler, Angler, Outdoor Worker, Field/Team Sports, Snow Sports, and Tactical Training, each tuned to its specific exposure and shelter-reach time | Not included | Included | Included |
| Custom activity profiles — create your own profiles for specialized activities; choose an activity type first, then tune the bounded tolerance controls relevant to that activity (heat, AQI, wind, waves, cold water, and low-risk-window rules). Safety guardrails remain locked — lightning safety, severe weather, and storm-model thresholds cannot be disabled or edited | Not included | Included | Included |
| Personal Profile — optional cross-profile tuning for age group, heat tolerance, air-quality sensitivity, and fitness level. Storm Window keeps the displayed weather numbers unchanged and adjusts only how risk is classified for your selected activity and personal characteristics | Not included | Included | Included |
| Full per-hour detail panel — every contributing factor with its measured value, hazard state, and activity-profile threshold; rows not relevant to the current activity are hidden to keep the panel readable. Free shows a condensed summary only | Summary only | Included | Included |
| Risk Profile radar chart — inside the per-hour detail panel, a chart of the hazards driving that hour’s rating (lightning, heat, wind, wind chill, air quality, and for water activities, waves and water temperature) so you can see at a glance which factor to watch. Tapping an axis opens the same on-demand educational explanation as the Apple Intelligence educational cards below. A “Compare to now” action on Best Time Today shows the current hour side by side with the recommended window, whose chart shades each hazard’s low-to-high range across that window rather than a single reading | Not included | Included | Included |
| Driest-stretch highlight — within the current low-risk window, marks the consecutive run of hours with the lowest precipitation chance so you can time a workout around rain even when conditions are otherwise safe | Not included | Included | Included |
| Per-location widgets and complications — pin any saved location to a Home Screen widget, Lock Screen widget, or watch complication so you can monitor multiple places at a glance without switching the active location; watch complications can also pin an activity | Not included | Included | Included |
| Other-locations ticker — a scrolling banner of cached conditions for your other saved places, ranked most-urgent first, so you can spot a developing situation at another location without leaving the current view | Not included | Included | Included |
| Pro+ Safety Alerts — additional alert types scheduled from cached forecasts: window-change (safe window opens or closes), best-window-starting (the safest stretch of the day is about to begin), next-window-changed (tomorrow’s window shifted), and daily briefing; covers saved locations that are eligible for monitoring | Not included | Not included | Included |
| Apple Watch location and activity controls — switch the active location and change the activity profile directly from the watch; touch and hold the Watch chart to switch between Bars and Dots; default watch complications follow those Watch app choices, while explicitly pinned complications stay pinned. Free users can only view the active location set on the iPhone | View only | Included | Included |
| Apple Intelligence hourly hazard explanations — on-device AI explains which factors drove a specific hour’s rating and why, using Storm Window’s deterministic assessment as the authoritative input. Falls back to Storm Window’s own plain-language explanation on devices without Apple Intelligence | Not included | Not included | Included |
| Apple Intelligence educational cards — on-demand explanations for individual risk factors (AQI, heat stress, lightning, UV, wind, waves, cold water, and more) tailored to the current conditions and activity profile | Not included | Not included | Included |
| “Should I Go?” advisor — activity-aware recommendation for the current planning period, weighing all active factors and your profile against your stated intensity and duration; includes an optional plain-language explanation | Not included | Not included | Included |
| “Changed Since Last Update” — when a new forecast makes conditions worse than the previous fetch, Storm Window explains exactly what changed and why the window shifted, so you know whether to adjust plans | Not included | Not included | Included |
| 3-Day Summary — an AI-generated plain-language overview of the forecast ahead: best window timing, unsafe blocks, and which hazards are driving the risk so you can plan beyond the next few hours. Pro+ can use server-generated summaries when enabled, with Apple Intelligence and deterministic fallback paths still available | Not included | Not included | Included |
| Shareable snapshots — export a summary card showing the current safe window, risk chart, and key conditions, or a Plan card showing a Plan’s scheduled or recommended window and outlook, to share with training partners, coaches, or anyone else planning the same outing | Not included | Not included | Included |
| Plans — pin a future start time, end time, place, and activity (a race, tee time, swim meet, outdoor work shift, or other outdoor commitment), including Plans beyond the normal 72-hour home view. Choose a fixed time or a flexible earliest/latest range that Storm Window uses to recommend the best start inside it, with a forecast-trend indicator (improving, worsening, stable, or just shifted in time) and an optional plain-language explanation of why that start was chosen. Storm Window monitors the Plan as forecast data becomes available, independent of your saved locations, and can suggest a better-rated nearby time when a fixed Plan’s window turns risky. Turn on Plan forecast changed alerts to be notified if conditions worsen as the date approaches | Not included | Not included | Included |
Risk factor roles
Factors fall into three categories: verdict inputs that can close the low-risk window, internal model signals that feed the verdict but are not shown individually, and advisories that provide planning context without changing the window. This separation keeps Storm Window focused on outdoor safety instead of turning it into a general weather dashboard.
Default activity thresholds are grounded in published weather, public-health, sports-medicine, and marine guidance. See Threshold Sources for reference links.
| Risk factor | Role and how Storm Window uses it | Shown to users | Activity scope |
|---|---|---|---|
| Lightning / thunderstorm risk | Verdict input. The primary safety signal. Likely lightning closes the low-risk window entirely. Possible lightning is a caution heads-up in Standard mode and also closes the window in Cautious Lightning mode. The risk level is scored per hour from atmospheric instability and, in the U.S., NWS thunder probability. | Yes — as the storm/lightning status line, in per-hour detail, and as native Lightning Map context when available | All outdoor activities. Exposed and slow-to-shelter activities (golf, open water, boating) use a more cautious probability threshold. |
| NWS probabilistic thunderstorm forecast | Primary U.S. lightning model input. The National Weather Service hourly thunder probability is the dominant signal for lightning risk in the contiguous United States where available. Outside the U.S., or when NWS data is absent, Storm Window falls back to atmospheric instability (CAPE, CIN, and lifted index) with a dry-lightning classifier for arid western regions. | Yes — shown as a percentage in the per-hour detail panel when available | All outdoor activities in the United States. |
| NWS active alerts | Verdict input. Official NWS watches, warnings, and advisories for relevant hazard types — severe storms, tornado, flash flood, extreme wind, extreme heat, extreme cold, beach and rip current hazards, and high surf — contribute to the risk rating. The hourly chart draws a thin NWS overlay when official guidance is more cautious than the matching local model data, so you can see both together. | Yes — as an overlay on the risk chart and as a heads-up card | Filtered by activity: beach, marine, and rip-current alerts are hidden for unrelated activities such as running or cycling. |
| CAPE, CIN, and lifted index | Internal storm-model signal. Convective Available Potential Energy, Convective Inhibition, and lifted index are the atmospheric instability inputs that drive storm risk estimation worldwide, and form the fallback lightning signal outside the U.S. Raw values are never shown to users; they are folded into the lightning and storm risk score. | No — folded into the verdict. Raw values appear only in the debug diagnostics screen. | All outdoor activities through the storm and lightning risk score. |
| Heat index | Verdict input. NWS heat index (temperature + humidity) closes the low-risk window when it reaches dangerous levels. Heat index is the primary displayed heat value in per-hour detail and acts as the safety floor when WBGT-like data is available. | Yes — as the displayed heat value and as a factor in per-hour detail | All outdoor activities. Pro custom profiles can tune the caution and unsafe thresholds within bounded ranges. |
| Estimated heat stress (WBGT-like) | Verdict input. A Wet Bulb Globe Temperature–like estimate that adds solar radiation and weighted humidity on top of the standard heat-index calculation. When enough forecast inputs are available (temperature, humidity, wind, and cloud/solar data), this is the primary heat safety signal; heat index serves as fallback. WBGT reads on a numerically lower scale than “feels like,” so a Heat Stress Index of 88 °F already represents serious risk — which is why its default thresholds are set lower than Air Temperature thresholds. | Yes — as the Heat Stress Index value in per-hour detail | All outdoor activities. Pro custom profiles can tune bounded thresholds separately from the heat-index thresholds. |
| Air Quality Index (AQI) | Verdict input. AQI from Open-Meteo’s air quality forecast closes the low-risk window when particulate or ozone levels make sustained outdoor activity unhealthy. Thresholds are based on EPA AQI breakpoints and activity-specific guidance. | Yes — as the AQI value and category in per-hour detail | All outdoor activities. Pro custom profiles and the Personal Profile can tune AQI sensitivity. |
| Wind gusts | Verdict input. Dangerous gust speeds close the low-risk window independent of storms. Thresholds differ by activity: a gusting headwind that is unpleasant for a cyclist can be genuinely hazardous for an open-water swimmer or a paddler, so each profile sets its own gust limits. | Yes — as the gust speed in per-hour detail and as native Wind Map context when available | All outdoor activities with activity-specific thresholds. Pro custom profiles can tune bounded gust tolerances. |
| Wind chill | Verdict input. Calculated wind chill closes the low-risk window when cold exposure reaches frostbite or hypothermia risk. More conservative thresholds apply to sustained or high-exposure activities where stopping to warm up is difficult. | Yes — as the wind chill value in per-hour detail during cold conditions | All outdoor activities, with more conservative handling for exposed or sustained efforts. |
| Wave height and sea state | Verdict input for water activities. Significant wave height and swell period from the Open-Meteo Marine API close the low-risk window when conditions exceed the safe operating envelope for the activity — small boat, sailboat, paddler, open-water swimmer, and similar profiles each have their own wave limits. | Yes — shown only for relevant activities when marine data is available | Beach, swimming, boating, sailing, paddling, fishing, and related water activities. |
| Sea surface / water temperature | Verdict input for water activities. Cold sea-surface temperature closes the low-risk window when immersion risk rises to hypothermia territory. Thresholds scale by activity: a recreational open-water swimmer and an offshore boater face different time-to-incapacitation curves. | Yes — shown only for relevant activities when marine data is available | Beach, swimming, boating, sailing, paddling, fishing, and related water activities. |
| UV index | Advisory only. UV index is a sun-protection planning signal and does not close the low-risk window on its own. It helps you decide whether to apply sunscreen, cover up, or limit midday exposure, without inflating the risk rating for a clear-sky afternoon run. | Yes — as a planning advisory with category label (Low / Moderate / High / Very High / Extreme) | All outdoor activities as advisory context. |
| Altitude / elevation | Advisory only. For mountain profiles (Hiker, Climber, Tactical Training) at locations above approximately 5,000 ft, Storm Window shows an altitude-illness advisory banded by elevation per CDC Yellow Book guidance. Because altitude is a fixed property of the location rather than a changing forecast input, it never closes the low-risk window by itself. | Yes — as an advisory card for mountain profiles above the elevation threshold | Mountain profiles (Hiker, Climber, Tactical Training) at relevant elevations. |
| Rain, snow, and sky condition | Planning context. Precipitation probability and WMO weather code drive the sky-condition label (Clear, Partly cloudy, Overcast, Rain, Snow, etc.) and the optional rain/snow overlay on the risk chart. Precipitation alone does not close the low-risk window; it is informational context for comfort and preparation. The overlay can be toggled on or off in Settings. | Yes — as the sky-condition label alongside the verdict, and as an optional chart overlay | All outdoor activities as planning context. |
| Air temperature | Display context and fallback input. Apparent temperature (“feels like”) is shown as a comfort reference. Heat index, estimated heat stress, and wind chill carry the actual safety meaning; air temperature is the fallback heat signal only when neither can be computed from available forecast data. | Yes — as the current and hourly temperature display | All outdoor activities as display context. |
Storm Window provides forecast guidance and weather-risk context only. It is not a certified lightning safety system, emergency alert system, medical app, or guarantee of safe conditions. Do not wait for Storm Window: when thunder roars, go indoors.