Most weather apps give a number; they don't help you decide. "12 °C with rain" — is that a go or no-go? It depends on the rest of the forecast and the kind of riding you planned. This tool weighs multiple risk factors and gives you a single verdict plus a checklist of specific things to watch for.
| Risk | Level | Why |
|---|
The hard "no-go" conditions are few: lightning, ice on roads, or visibility below ~200 m. Everything else is a judgment call. A commute to work in drizzle at 5 °C is reasonable; a 4-hour training ride in the same drizzle at 2 °C probably isn't.
This calculator is conservative on safety (no-go for lightning, ice, near-zero visibility) but lets the rider override on a case-by-case basis. Use the verdict as a starting point, not a verdict.
Lightning strikes cyclists with tragic regularity. Open roads, exposed body position, and conductive bike parts make cycling in a lightning storm one of the highest-risk outdoor activities. Stay home.
For the bike: yes. Snow on roads is usually manageable if it's not too deep. Sleet stings but doesn't ice. Freezing rain turns roads into black-ice rinks instantly. We treat freezing rain as a "no" because of that ice risk.
Wind + cold + gusts is the danger. Steady 20 km/h at 5 °C is fine; 20 km/h with 50 km/h gusts at -2 °C is a different ride. We weight the gusts in.
This calculator was built to answer a question most online versions skip or oversimplify. It runs entirely in your browser; no inputs are stored or transmitted. The math is grounded in standard cycling physics and physiology models, and is suitable for hobbyist and intermediate training use. It is not a substitute for a coach, sports scientist, or professional bike-fit service.
This tool does not collect personal data. All inputs and results stay in your browser. We do not set first-party analytics cookies. This site may display ads served by Google AdSense; Google, as a third-party vendor, uses cookies to serve ads based on a user's prior visits to this site or other sites. Google's use of advertising cookies enables it and its partners to serve ads based on the visit to this site and/or other sites on the Internet. You can opt out of personalized advertising by visiting Google Ads Settings (google.com/settings/ads). Third-party vendors, including Google, use cookies to serve ads based on a user's prior visits to this site or other sites.
Children under 13 are not the intended audience.
This calculator is provided for general informational and educational purposes only. It is not medical, mechanical, or legal advice. Predicted values depend on inputs you supply and simplified physical models; real-world outcomes vary. Use at your own risk. Brand names are descriptive only and do not imply affiliation.