Free running weather calculator

Running Weather Calculator

Enter your city. Get a 0–100 Run Score, the best window to run today, and exactly how heat, dew point, and wind are changing your effort — using the same engine that powers the RunWeather app.

Live running weather workbenchTemperature · dew point · wind · timing

Free · no account needed · works for any city worldwide.

What the calculator scores

The Run Score is not a single reading dressed up. Eight weather signals are weighted by how much each one actually changes a run, then combined into one decision.

Temperature

Performance peaks near 50–54°F. Every degree above that taxes your cooling system and slows the pace you can hold at the same effort.

Dew point

The real humidity signal. Above ~60°F dew point, sweat stops evaporating efficiently — the single biggest hidden driver of a hard summer run.

Wind

Headwinds cost pace and gusts break rhythm. The model weighs sustained speed and direction, not just the headline number.

Heat stress

How hard heat, humidity, sun, and wind hit your body, combined into one number (wet-bulb globe temperature) — the same metric race directors use to flag risk.

Solar exposure

Direct radiation on a shadeless route can feel far hotter than the air temperature. Cloud cover and sun angle are factored in.

Precipitation

Rain probability and intensity affect footing, comfort, and gear — weighted by how likely it is during your window.

Air quality

US AQI is folded in so sensitive runners get a clear signal when particulates make hard efforts a bad idea.

Pace adjustment

The output you actually use: how many seconds per mile to give back today so your effort — not the clock — stays honest.

How it works

01

Enter your city

Search any city worldwide. RunWeather pulls the live local forecast — temperature, dew point, wind, sun, and air quality.

02

Get a 0–100 Run Score

One number that blends performance, safety, and experience — labeled Perfect, Great, Good, Mixed, or Poor — for the current hour.

03

Scrub the next 12 hours

Tap any hour to rebuild the full breakdown for that start time, or jump straight to the best window today.

Best time to run, by city

Live Run Scores and the best window today for running hotspots worldwide. Same engine, every climate.

Running weather guides

How each kind of weather changes your run — and the cities where it matters most.

Running in the heat Running in high humidity Running in the cold Running in wind

Running weather calculator FAQ

What is a good Run Score?

Scores run 0–100. 97+ is Perfect, 80–96 is Great — conditions are actively working in your favour. 65–79 (Good) is solid. 45–64 (Mixed) means at least one factor — usually heat or dew point — is taxing you. Below 45 (Poor), expect a noticeably harder effort or hold back for safety.

Why does dew point matter more than temperature?

Your body cools by evaporating sweat. When the dew point climbs above roughly 60°F, the air is too saturated for sweat to evaporate efficiently, so heat builds up even if the thermometer looks reasonable. That's why a 70°F muggy morning can feel harder than a dry 80°F afternoon.

How is this different from a normal weather app?

A weather app tells you the conditions. This calculator translates them into a running decision: a single score, the best hour to head out, and a concrete pace adjustment in seconds per mile — using the same scoring engine that powers the RunWeather app.

Is the running weather calculator free?

Yes. The calculator is completely free to use, with no account required. The RunWeather app adds Strava sync, multi-day planning, and personalized heat acclimation on top of the same model.

Get this on every run, automatically

RunWeather syncs with Strava, plans your week, and learns your heat tolerance — so the right time to run finds you.

See plans How RunWeather works