| Night evening → next morning |
Min temp* overnight low |
Hours ≥ 20° (range) |
Hours ≥ 25° (range) |
Overnight curve 21:00 → 09:00 |
|---|
* Temperatures on this site are “feels like” values — see the note below.
Hourly forecast, next 7 days — 🔗
Temperature line — grey = observed up to “now”, blue = forecast after it (the ensemble median). The blue shaded envelope around the forecast is the 10–90% range across the 40-member ensemble — how uncertain it is. The vertical “night” bands are the overnight windows (21:00–09:00), where the temperature bottoms out; gaps are daytime. Dashed lines mark 20° and 25°.
All cities at a glance — warmest overnight low
Each cell is that night's overnight low (the coolest the temperature gets). A higher number is a warmer, worse night — ≥ 20° and ≥ 25° are shaded.
How to read this
Each night runs 21:00 to 09:00 the next morning in the city's local time, so a row labelled “Sun 5 → Mon 6” is the night from Sunday evening into Monday morning. The colours flag how warm it stays: sleep gets worse continuously as nights warm, but as rough benchmarks a temperature that stays above 20° all night means a warm, restless night for people without air-conditioning, and above 25° all night is oppressive, with very poor sleep.
More views: the public-health / epidemiology angle — heat-mortality risk for vulnerable groups, tonight vs each city's historical climate, past excess-mortality summers — at Summer Night · Epi →, and how well the forecast verifies against observations at Forecast skill →
Uncertainty: the big number in the “hours ≥ threshold” columns is the best-estimate forecast — the same run drawn as the line in the chart, so the two always agree. The small “X–Y hrs likely” underneath is the 10th–90th percentile spread across the 40-member ICON weather ensemble, i.e. how uncertain that number is. On unsettled nights the best estimate can sit near the edge of that range.
Important caveat: we forecast outdoor temperature, but what affects sleep and health is the temperature in the bedroom. Homes without air-conditioning often stay warmer than the outside air overnight and cool more slowly, so indoor conditions can be worse than these numbers suggest. Thresholds are indicative, not an official heat warning — follow your national weather service for alerts.
* Every temperature on this site is a “feels like” value — the apparent temperature (Steadman shade formula), which adjusts the air temperature for humidity and wind because humid air slows the body's cooling by sweat. It has no sunshine term, so it is the right version for overnight; on humid nights it reads a little above the plain air temperature. We use it because a review of the heat literature found apparent temperature, not WBGT or wet-bulb, is the humidity-inclusive index that holds up in temperate Europe.