Find the safest time to run in the next 48 hours — when you live somewhere hot.
Weather apps show numbers; CoolRun answers the question runners in places like Dubai actually have: when should I go? It scores every hour of the forecast for heat risk — feels-like temperature, sun (UV), humidity, breeze — adjusted for your run length, effort and heat tolerance, then recommends the best window, explains why, and adds it to your calendar.
- City search (or "use my location") with live forecasts from Open-Meteo — free, no API key.
- Best run window + two alternatives ≥3 h apart, with risk band (Ideal → Danger) and plain-English reasons.
- 48-hour heat ribbon; hover any hour for details.
- Instant re-planning when you change run length (20–120 min), effort, or heat tolerance.
- One-tap
.icscalendar export with a 30-minute reminder. - Offline demo data (Dubai) so it always works.
Requires Node.js 18+. No dependencies to install.
node server.mjs
# open http://localhost:5173(Any static server pointed at app/ also works, e.g. python3 -m http.server -d app.)
Tests: node --test test/
effective = feels-like + 0.6×UV (daytime) + 0.08×(humidity−60) − 0.08×wind(≤30 km/h) + effort(0/1.5/3) − tolerance(−2/0/+2)
Bands: <24 °C Ideal · <28 Good · <32 Caution · <36 High risk · ≥36 Danger. A window's risk is its worst hour; best = lowest risk, soonest first.
These are heuristic guidance thresholds — not medical advice.
app/ the web app (index.html, styles.css, main.js, api.js, scoring.js, ui.js, ics.js, sample-dubai.json)
test/ node:test unit tests for the scoring logic
server.mjs zero-dependency static server
video/ headless Playwright script used to record the demo
devpost/ planning docs from the Devpost Learn skill pack: scope.md, prd.md, spec.md, checklist.md
Plain HTML/CSS/JavaScript, Open-Meteo APIs, Node.js. Planned and built with the Devpost Learn skill pack and an AI coding agent.
Weather data by Open-Meteo.com (CC BY 4.0). License: MIT.