Climate averages 1991–2020
Thornton weather
in May.
A mild, moderately wet month: the 5th warmest and the wettest of the year.
Long-term climate patterns, not a forecast for a particular trip.
May is a mild month in Thornton: daytime highs average 19.6°C and nights cool to about 5.3°C. By daytime temperature it is the 5th warmest of the 12 months.
Expect about 82 mm of rain on roughly 11 days, which makes May a moderately wet month (the wettest month of the year). Daylight, from sunrise to sunset, lasts about 14 h 21 min on an average May day.
The nearest other city in this atlas is Westminster (Colorado), United States (7 km away). In May its highs average 19.6°C, about as warm as Thornton, with 82 mm of rain.
Among the 498 cities listed in the United States, Thornton ranks joint 406th of 498 for the warmest May highs and joint 228th of 498 for the driest May (rainfall, lowest first). The mean May high of those 498 cities is 23.8°C; Thornton is 4.2°C cooler than that mean.
From May to June, average highs rise by 6.3°C to 25.9°C, and monthly rainfall falls from 82 mm to 52 mm.
The annual picture
May in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Thornton climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 4.3°C-9.7°C | -9.7°C | 22 | 5.2 | 9.710 h |
| February | 5.7°C-8.7°C | -8.7°C | 23 | 5.9 | 10.711 h |
| March | 10.7°C-4.9°C | -4.9°C | 47 | 7.6 | 11.912 h |
| April | 14.4°C-0.4°C | -0.4°C | 70 | 9.9 | 13.213 h |
| May, selected | 19.6°C5.3°C | 5.3°C | 82 | 11.0 | 14.414 h |
| June | 25.9°C10.8°C | 10.8°C | 52 | 8.3 | 14.915 h |
| July | 29.2°C14.5°C | 14.5°C | 41 | 7.2 | 14.715 h |
| August | 28.0°C13.8°C | 13.8°C | 39 | 6.4 | 13.714 h |
| September | 24.0°C9.4°C | 9.4°C | 36 | 5.8 | 12.512 h |
| October | 16.6°C2.3°C | 2.3°C | 40 | 6.1 | 11.211 h |
| November | 9.4°C-4.9°C | -4.9°C | 30 | 5.9 | 10.010 h |
| December | 4.0°C-9.7°C | -9.7°C | 21 | 4.9 | 9.49 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
May in nearby cities
- Westminster (Colorado), United States in MayUnited States · 7 kmHigh 19.6°C · Low 5.2°C · 82 mm rain
- Arvada in MayUnited States · 12 kmHigh 19.6°C · Low 5.1°C · 82 mm rain
- Denver in MayUnited States · 14 kmHigh 19.7°C · Low 5.2°C · 82 mm rain
- Aurora (Colorado), United States in MayUnited States · 20 kmHigh 20.7°C · Low 6.7°C · 63 mm rain
- Lakewood in MayUnited States · 20 kmHigh 19.6°C · Low 5.0°C · 82 mm rain
- Boulder in MayUnited States · 30 kmHigh 19.2°C · Low 5.1°C · 103 mm rain
- Centennial in MayUnited States · 33 kmHigh 19.2°C · Low 4.8°C · 88 mm rain
- Highlands Ranch in MayUnited States · 35 kmHigh 19.2°C · Low 4.5°C · 88 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Thornton) is explained once on the Thornton year overview and on the Sources, method and limits page.
Denver, Lakewood and Westminster (Colorado), United States lie in the same rainfall cell, so their rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.