WhatAWeatherBest time to run or ride today
Every hour of the next 7 days scored from 0 to 10 for going out running or cycling: feels-like temperature, UV index, wind, rain, humidity and air quality. With today's best window and the best day of the week.
Today
Frequently asked questions
How is each hour's score calculated?
We combine the Open-Meteo hourly forecast with CAMS air quality: apparent temperature (what your body feels under effort), UV index, rain probability and intensity, mean wind and gusts, relative humidity and the European air quality index (EAQI). Each factor scores from 0 to 1 according to its effect on performance and the final score is expressed from 0 to 10. The weights change by sport: when running, heat is penalised more; on the bike, wind and wet roads.
What is the ideal temperature for running or cycling?
For running, peak performance occurs with a feels-like temperature between 8 and 16 °C: the body generates a lot of heat and welcomes cool air. On the bike, the benefit of the relative wind allows a somewhat warmer range, from 10 to 20 °C. Above a 28 °C feels-like, performance drops clearly and the risk of heat stroke increases; below 0 °C it is wise to protect airways and extremities.
Is it bad to train with poor air quality?
During exercise you ventilate 10 to 20 times more air than at rest, so pollutants (PM2.5, ozone) reach your lungs in a much higher dose. With the European EAQI index above 60-80 it is wise to shorten or ease the session, and with very high values it is preferable to train indoors. Ozone usually peaks on sunny summer afternoons: another reason to get up early.
Can I trust the score for training at night?
Night hours are scored the same way (and in summer they are often the best thermally), but they are marked with a moon because the score only measures weather: it does not assess visibility, traffic or route safety. If you train at night, add reflective gear and lights, and choose well-lit, familiar routes.
The best time to train is not an opinion: it can be calculated
Any runner or cyclist knows that the same workout can be a pleasure at 7:30 and a punishment at 15:00. The difference is rarely fitness: it is weather applied to effort. This tool scores every hour of the next seven days by combining the six factors that most affect an outdoor session.
Apparent temperature, the dominant factor
We use the apparent temperature (feels-like) rather than the thermometer reading, because it integrates humidity, wind and radiation. When running, the body generates so much heat that the optimal band is between 8 and 16 °C; on the bike, the constant airflow shifts the optimum to 10-20 °C. From a 28 °C feels-like upwards, heart rate rises for the same effort, pace per kilometre drops and the risk of heat stroke soars, especially if humidity exceeds 85% and sweat stops evaporating.
UV, wind, rain and the air you breathe
The UV index penalises from 6 upwards (in a one-hour session in the sun, unprotected skin burns in under 20 minutes with high UV). Wind costs more on the bike, where from 20-25 km/h it dictates the route and gusts compromise stability; running tolerates it better. Rain also weighs differently: getting wet while running is uncomfortable, but wet asphalt on a bike multiplies the risk of a crash. And air quality (European EAQI index with PM2.5 and ozone) matters more than it seems: under effort you ventilate up to 20 times more air, so we penalise hours with EAQI above 60.
How to read the results
Today's recommended window is the best two-hour block still ahead; the afternoon alternative gives you a plan B if you can't get up early, and the hours-to-avoid warning flags the most hostile stretch of the day. The 48-hour chart lets you plan the next day, and the weekly view highlights the best moment of the next seven days for the long session. Night hours score the same, but are marked with 🌙: the score measures weather, not the safety of running in the dark.
Data comes from Open-Meteo (high-resolution weather models and Copernicus CAMS air quality) and is updated every hour. This is sport guidance based on a forecast, not medical advice: under official extreme heat warnings, the session moves indoors or doesn't happen.