Thornton, Colorado Weather
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Climate of Thornton: monthly averages
Based on 25 years of satellite and reanalysis data (2001-2025), July is usually the hottest month in Thornton, with average daytime highs around 32°C. February is the coolest, when nights typically fall to about -7°C and frost is possible on the coldest nights. That is a wide yearly range of roughly 39°C, so the seasons feel very different from each other.
The area receives about 450 mm of rain in a typical year. Rainfall is modest in every month; May is the wettest at about 65 mm.
For outdoor plans and travel, May to September usually offer the most comfortable weather in Thornton, with mild days and relatively little rain.
| Month | Avg high | Avg low | Rainfall | Humidity |
|---|---|---|---|---|
| Jan | 5° | -6° | 20 mm | 55% |
| Feb | 6° | -7° | 24 mm | 56% |
| Mar | 12° | -3° | 36 mm | 51% |
| Apr | 16° | 1° | 54 mm | 49% |
| May | 22° | 6° | 65 mm | 49% |
| Jun | 29° | 12° | 43 mm | 41% |
| Jul | 32° | 16° | 52 mm | 42% |
| Aug | 30° | 15° | 43 mm | 43% |
| Sep | 26° | 10° | 36 mm | 42% |
| Oct | 18° | 2° | 33 mm | 47% |
| Nov | 11° | -3° | 21 mm | 51% |
| Dec | 4° | -7° | 21 mm | 57% |
Source: NASA POWER (MERRA-2 reanalysis), averaged over the roughly 50 km grid area around Thornton. Values describe typical conditions, not a forecast.
About Thornton weather
Thornton, in Colorado's high-altitude climate, ranging from semi-arid plains to alpine mountains, is positioned about 14 km north of Denver. The warmer months mean warm days and cool nights (June–August), especially at altitude. Finally, there's cold, snowy winters in the mountains, milder on the eastern plains. This page shows live, auto-refreshing weather for Thornton: current conditions, an hourly breakdown, a 16-day outlook, a date-lookup tool for any past or future date, and real-time air quality, sourced from Open-Meteo. Local timezone: America/Denver.
Frequently asked questions
Thornton is about 14 km north of Denver, in Colorado.
Thornton sees cold, snowy winters in the mountains, milder on the eastern plains.
The live current conditions, hourly forecast and 16-day outlook above are pulled in real time for Thornton's exact coordinates. No fixed schedule, the page updates whenever you load it.
July is usually the hottest month in Thornton, with average daytime highs of about 32°C and nights around 16°C.
The coldest nights come in February, when the average low is about -7°C and daytime highs reach around 6°C. Frost is possible on clear, calm nights.
Thornton receives about 450 mm of rain in a typical year. May is the wettest month at roughly 65 mm; no month averages more than 100 mm.
May to September usually offer the most comfortable weather in Thornton, with mild daytime temperatures and little rain.
In November Thornton typically sees daytime highs near 11°C and lows near -3°C, with about 21 mm of rain over the month and average humidity around 51%. Check the live forecast above for this week's actual conditions.
Up to 16 days ahead using the extended forecast and date picker above; further-out or historical dates use the same date lookup tool.
The current temperature for Thornton updates automatically at the top of this page — scroll to the hourly strip below to see how it's expected to change over the day.
Thornton's day-to-day weather follows the broader pattern of Colorado described above. See the hourly weather forecast or the air quality index for more detail.