Too little checked to say Store information only. We haven’t analysed this app or read its reviews yet.
Not yet tested.
The store currently lists version 1.6.5, updated 2026-10-17.
Store screenshots supplied by the developer.
How risky is today's heat? Swelter tracks the WBGT, wet bulb temperature, and heat index hour by hour, finds the best window in your day, and alerts you before extreme heat arrives. Validated against 20k+ hours of station data.
Your local conditions become one of four flags: GOOD TO GO, CAUTION, HIGH RISK, or CANCEL. The flags follow the American College of Sports Medicine's published WBGT thresholds, a scale built for heat safety during outdoor exertion in the sun.
The heat index tells you how hot it feels in the shade. WBGT (wet-bulb globe temperature) also counts direct sun and wind, so it reflects how well your body can actually cool itself. It is the standard measure of heat stress, used worldwide for decades to decide when to limit outdoor activity. Swelter computes it on your phone from Apple Weather data.…
From the developer’s store description.
For developers and the curious
The evidence, sources, measurements and versions behind every label above.
No review analysis published for this app.
“Not assessed” means we could not measure it. It is never a zero and never a pass.
No package has been scanned for this app, so nothing is published about what it ships. That is an absence of evidence, not a finding.
Supporting measurements: not a complete list of possible harms or positives. Measurement vocabulary 1.4 · how these are measured
Not yet tested. No analysis has been run for this app, so there is no version or date to report.
Each store’s release notes, as the developer wrote them. They are the developer’s words, not ours.
- Improved the "Near" line. It now appears when a reading sits within 2 °F (1.1 °C) of a flag boundary, instead of 1 °F (0.6 °C). This is a small display change only, so heat risk is shown more prominently when forecast data sits near a boundary. - The Sunrise/Sunset screen on the Apple Watch app now switches to showing tomorrow's sunrise once the sun has set.
Appworthy
wet-bulb-temperature-apple-6794481096What the stores publish. Store ratings are the stores’ numbers, not Appworthy’s, and are never averaged across stores.
From the store listing. Billing terms are read from each purchase’s name — the stores don’t publish them — so treat them as a strong hint, not a disclosure.
Not yet tested. No analysis has been published for this app, so there is no method to describe for it yet. A missing label is not a clean bill of health: it means nothing has been read, not that nothing is wrong.
Write to [email protected], or use the form. Name the finding, the app version and the evidence that needs correcting. Factual corrections are free and never depend on buying anything.