Live heat risk, updates hourly
Where It's Too Hot to Run Today
Air temperature is not what makes a run feel dangerous. Dew point is. When the dew point climbs above about 60°F (16°C), sweat stops evaporating efficiently, so the body cannot cool itself even when the thermometer looks reasonable.
- ★★★★★5.080+ ratings
- 2,500+runners
- 100countries
The numbers
Hottest heat risk right now
The five cities carrying the worst heat stress today, ranked by estimated WBGT.
Live data for 57 of 57 cities.
- 1Bangkok, ThailandExtreme heat stressPeak 91°F · dew point 73°F · Run Score 28
- 2Dubai, United Arab EmiratesExtreme heat stressPeak 94°F · dew point 69°F · Run Score 46
- 3Brisbane, AustraliaExtreme heat stressPeak 89°F · dew point 69°F · Run Score 48
- 4Singapore, SingaporeHigh heat stressPeak 85°F · dew point 74°F · Run Score 36
- 5Miami, United StatesHigh heat stressPeak 78°F · dew point 74°F · Run Score 56
A muggy 75°F (24°C) morning in a humid city can slow a runner more than a dry 95°F (35°C) afternoon in a desert one, because the dry city's sweat still evaporates.
Every score below is RunWeather's Run Score, the same 0 to 100 verdict the app shows a runner before they head out. Heat stress uses wet-bulb globe temperature (WBGT), the heat-strain mechanism race directors use to call off events, so a city can carry high heat stress even on a day that does not look extreme on a normal weather app.
A concrete example
Houston and Phoenix can both post a hot summer forecast, but they rarely carry the same risk. Houston's Gulf humidity keeps dew points in the 70s (Fahrenheit) for months, so sweat barely evaporates and the body keeps overheating, hour after hour. Phoenix runs hotter on the thermometer but far drier, so sweat still cools effectively and the heat stress reading is often lower, until the desert sun and low humidity push dehydration risk up instead. Same season, two different reasons to slow down. The dew point and WBGT columns above, not the raw temperature, are what to read first.
Every city, ranked worst first
All 57 cities, sorted by today's heat stress. Tap a city for its full hour-by-hour breakdown.
| City | Peak temp today | Dew point | Run Score | Heat stress | Best window today |
|---|---|---|---|---|---|
| Bangkok | 91°F (33°C) | 73°F (23°C) | 28 Poor | Extreme heat stress | No safe window today |
| Dubai | 94°F (35°C) | 69°F (21°C) | 46 Fair | Extreme heat stress | No safe window today |
| Brisbane | 89°F (32°C) | 69°F (21°C) | 48 Fair | Extreme heat stress | 6–7 AM |
| Singapore | 85°F (29°C) | 74°F (23°C) | 36 Poor | High heat stress | No safe window today |
| Miami | 78°F (26°C) | 74°F (23°C) | 56 Fair | High heat stress | 4–8 AM |
| Lima | 78°F (26°C) | 68°F (20°C) | 65 Good | High heat stress | 4–9 AM |
| Austin | 79°F (26°C) | 65°F (18°C) | 70 Good | High heat stress | 2–9 AM |
| Hong Kong | 86°F (30°C) | 65°F (18°C) | 56 Fair | High heat stress | 12–8 AM |
| San Diego | 80°F (27°C) | 58°F (14°C) | 67 Good | High heat stress | 12–8 AM |
| Dallas | 82°F (28°C) | 55°F (13°C) | 74 Good | High heat stress | 4–9 AM |
| Nairobi | 82°F (28°C) | 52°F (11°C) | 83 Great | High heat stress | 12–8 AM |
| Houston | 74°F (23°C) | 65°F (18°C) | 80 Great | Moderate heat stress | 8–11 PM |
| Tokyo | 66°F (19°C) | 64°F (18°C) | 58 Fair | Moderate heat stress | 5–6 PM |
| São Paulo | 73°F (23°C) | 64°F (18°C) | 81 Great | Moderate heat stress | 8–11 PM |
| Sydney | 74°F (23°C) | 63°F (17°C) | 48 Fair | Moderate heat stress | 9–11 PM |
| Barcelona | 71°F (22°C) | 59°F (15°C) | 94 Great | Moderate heat stress | 12–9 AM |
| Cape Town | 72°F (22°C) | 54°F (12°C) | 43 Poor | Moderate heat stress | 1–3 PM |
| Lisbon | 71°F (22°C) | 54°F (12°C) | 95 Great | Moderate heat stress | 1–7 AM |
| Nashville | 75°F (24°C) | 52°F (11°C) | 85 Great | Moderate heat stress | 12–4 AM |
| San Francisco | 73°F (23°C) | 51°F (10°C) | 71 Good | Moderate heat stress | 12–8 AM |
| Chicago | 73°F (23°C) | 50°F (10°C) | 92 Great | Moderate heat stress | 5–9 AM |
| Rome | 72°F (22°C) | 49°F (10°C) | 100 Perfect | Moderate heat stress | 12–9 AM |
| Los Angeles | 83°F (28°C) | 48°F (9°C) | 72 Good | Moderate heat stress | 2–8 AM |
| Phoenix | 80°F (27°C) | 45°F (7°C) | 72 Good | Moderate heat stress | 2–7 AM |
| Dublin | 63°F (17°C) | 59°F (15°C) | 76 Good | Low heat stress | 2–3 AM |
| London | 61°F (16°C) | 58°F (14°C) | 68 Good | Low heat stress | 4–6 AM |
| Manchester | 59°F (15°C) | 57°F (14°C) | 62 Fair | Low heat stress | 3–8 AM |
| Edinburgh | 60°F (16°C) | 56°F (13°C) | 43 Poor | Low heat stress | 4 PM |
| Paris | 57°F (14°C) | 55°F (13°C) | 76 Good | Low heat stress | 4–8 AM |
| Seoul | 67°F (19°C) | 52°F (11°C) | 87 Great | Low heat stress | 6–11 PM |
| Wellington | 62°F (16°C) | 51°F (11°C) | 30 Poor | Low heat stress | No safe window today |
| Toronto | 61°F (16°C) | 50°F (10°C) | 82 Great | Low heat stress | 10 AM |
| Perth | 67°F (19°C) | 50°F (10°C) | 74 Good | Low heat stress | 6–8 AM |
| Seattle | 55°F (13°C) | 49°F (10°C) | 100 Perfect | Low heat stress | 5–11 PM |
| Washington, D.C. | 67°F (20°C) | 49°F (10°C) | 100 Perfect | Low heat stress | 9–10 AM |
| Mexico City | 68°F (20°C) | 49°F (9°C) | 68 Good | Low heat stress | 3–6 AM |
| Atlanta | 70°F (21°C) | 48°F (9°C) | 84 Great | Low heat stress | 7–9 PM |
| Portland | 51°F (11°C) | 48°F (9°C) | 94 Great | Low heat stress | 6–11 PM |
| Vancouver | 50°F (10°C) | 46°F (8°C) | 91 Great | Low heat stress | 5–6 PM |
| Amsterdam | 57°F (14°C) | 46°F (8°C) | 43 Poor | Low heat stress | 8–9 AM |
| Auckland | 71°F (21°C) | 45°F (7°C) | 57 Fair | Low heat stress | 12–3 AM |
| Stockholm | 50°F (10°C) | 45°F (7°C) | 46 Fair | Low heat stress | 10–11 PM |
| Melbourne | 58°F (14°C) | 42°F (6°C) | 52 Fair | Low heat stress | 9–11 PM |
| Salt Lake City | 60°F (16°C) | 42°F (6°C) | 100 Perfect | Low heat stress | 9–11 AM |
| Buenos Aires | 61°F (16°C) | 42°F (6°C) | 88 Great | Low heat stress | 10–11 PM |
| Las Vegas | 72°F (22°C) | 42°F (5°C) | 80 Great | Low heat stress | 3–8 AM |
| Madrid | 72°F (22°C) | 41°F (5°C) | 99 Perfect | Low heat stress | 12–6 AM |
| Philadelphia | 67°F (20°C) | 41°F (5°C) | 96 Great | Low heat stress | 10 AM |
| Berlin | 56°F (13°C) | 40°F (5°C) | 69 Good | Low heat stress | 7–11 PM |
| Montreal | 59°F (15°C) | 39°F (4°C) | 76 Good | Low heat stress | 6–7 PM |
| Denver | 56°F (13°C) | 38°F (3°C) | 90 Great | Low heat stress | 8–10 PM |
| Vienna | 56°F (14°C) | 38°F (3°C) | 52 Fair | Low heat stress | 6–10 PM |
| Munich | 52°F (11°C) | 38°F (3°C) | 62 Fair | Low heat stress | 4–11 PM |
| New York City | 65°F (19°C) | 36°F (2°C) | 92 Great | Low heat stress | 9–10 AM |
| Minneapolis | 56°F (13°C) | 35°F (2°C) | 56 Fair | Low heat stress | 12–1 PM |
| Boston | 65°F (18°C) | 34°F (1°C) | 79 Good | Low heat stress | 6 PM |
| Calgary | 34°F (1°C) | 27°F (-3°C) | 65 Good | Low heat stress | 12 AM–1 PM |
Weather data by Open-Meteo.com (CC BY 4.0): today's forecast, or ERA5 averages for 2022–2024 where marked typical. RunWeather computed the Run Scores and heat stress from it.
Keep going
Heat risk for runners: FAQ
5 questionsWhy does dew point matter more than air temperature for heat risk?
Your body cools by evaporating sweat. When the dew point climbs above roughly 60°F (16°C), the air is already too saturated for sweat to evaporate efficiently, so heat builds up even on a day that does not look extreme on the thermometer. That is why a muggy 75°F morning can slow you more than a dry 95°F afternoon.
How is heat stress calculated on this page?
Heat stress uses an estimated wet-bulb globe temperature (WBGT), the heat-strain mechanism race directors use to decide whether to delay or cancel an event. It folds in temperature, dew point, sun, and wind, so it can flag risk even when air temperature alone looks moderate.
What is the Run Score shown for each city?
A 0-100 verdict for how running conditions feel right now, the same score the RunWeather app shows before a run. It blends heat, dew point, wind, sun, and precipitation into one number: 80+ is Great, 65-79 is Good, 55-64 is Fair, 45-54 is Tough, and below 45 is Poor.
How often does this page update?
Every hour, from each city's live hourly forecast. The ranking, temperatures, and best windows all refresh on that cycle.
What happens if live data is not available for a city?
That city falls back to its typical conditions for the current month, computed from three years of hourly ERA5 history (2022 to 2024), and is marked as an estimate in the table. The page is built to keep showing a genuine number instead of an error, which matters most on the exact days (a heat wave) when live data is most valuable.
Running weather guides
How each kind of weather changes your run, and the cities where it matters most.
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. Free on iPhone and Android.
On a computer? Scan with your phone camera to get the app.
