What is a good Run Score?

Scores run 0–100. 80–100 is Great (97+ earns a gold star for near-perfect conditions). 65–79 (Good) is solid. 55–64 (Fair) or 45–54 (Tough) means at least one factor (usually heat or dew point) is slowing 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, all from 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 scoring on top of the same model.

Is now a good time to run?

Run Score right now: New York City 85 London 66 Los Angeles 88 Sydney 68 Tokyo 96

Free running weather calculator. Type your city and get the Run Score for right now and the best hour today, from the same engine as the app.

QR code that opens RunWeather in your phone's app store

On a computer? Scan with your phone camera to get the app.

★★★★★5.080+ ratings
2,500+runners
100countries

Works with Apple Health

The app

One check a day, done for you

When to go
Every hour gets a Run Score. On this Austin day the best was 7 am at 94.
Why it feels hard
Tap any hour: what's against you and how much slower the same effort runs.
On your home screen
Widgets and a morning alert, no app to open.

RunWeather Today in Austin at 7 am: Run Score 94, great day to run

7 am · score 94

Why this score: 57 out of 100, 6.8% slower for the same effort, temperature is the biggest drag

3 pm · 6.8% slower

By city

Best time to run, by city

What the calculator scores
Eight signals, weighted by how much each changes a run
Temperature. Performance peaks near 50–54°F. Every degree above that works your cooling system harder 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. Sustained wind and gusts feed drag and thermal estimates. This public calculator uses a default route-exposure assumption because it does not know your running direction.
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 ease off today so your effort (not the clock) stays honest.
Enter your city. Search any city worldwide. RunWeather pulls the live local forecast: temperature, dew point, wind, sun, and air quality.
Get a 0–100 Run Score. One number that blends performance, safety, and experience (labeled Great, Good, Fair, Tough, or Poor) for the current hour.
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.
Need a pace target for the heat instead? Try the heat and humidity pace calculator.
Running guides
Heat, humidity, wind, cold
Questions runners ask
4 questions
What is a good Run Score?
Scores run 0–100. 80–100 is Great (97+ earns a gold star for near-perfect conditions). 65–79 (Good) is solid. 55–64 (Fair) or 45–54 (Tough) means at least one factor (usually heat or dew point) is slowing 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, all from 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 scoring on top of the same model.
From the blog
12 posts
All running weather articles

Know your best hour before you head out.

Free on iPhone and Android. No account needed.

On a computer? Scan with your phone camera to get the app.

Is now a good time to run?

One check a day, done for you

When to go

Why it feels hard

On your home screen

Best time to run, by city

How the score works

What the calculator scores

Running guides

Questions runners ask

What is a good Run Score?

Why does dew point matter more than temperature?

How is this different from a normal weather app?

Is the running weather calculator free?

From the blog

Know your best hour before you head out.