Thornton, United States experiences average highs of 18°C (64°F) and lows of 2°C (36°F) throughout the year. The climate is relatively dry, with only 7 rainy days per month on average. Sunshine is abundant, averaging about 10 hours per day. Average highs have warmed by 0.8°C (1.4°F) across the available records.
Thornton, United States Weather & Climate 2026
Monthly climate averages for Thornton, United States. Based on 10-year ERA5 reanalysis data.
Climate Overview
Drier season: Jan–Dec 
Wetter season: Mar–Aug At-a-Glance Climate Summary
Live Weather & Air Quality
Key figures
Climate Score
5.4/10
Best: June, July, August, September
UV Index
6
High
Temperature 18°C / 2°C
Feels Like 15°C / -1°C
Rainy Days 7
Rainfall 41 mm
Sunshine 10 h
Humidity 54%
Wind Speed 15 km/h
Dew Point 1°C
Snow Days 6 days
Frost Days 20 days
Hottest Month
31°C
July
Avg Low15°C
Rain8days
Coldest Month
-10°C
January
Avg High4°C
Rain5days
Driest Month
4days
December
Avg High7°C
Avg Low-7°C
Windiest Month
17 km/h
April (Gusts 37)
Worst Time to Visit
Consider avoiding January, February, March, December due to very cold temperatures.
Sun Position
Sunrise 05:32
Daylight 15h
Sunset 20:31
Live conditions—
Thornton on the map · live conditions
Thornton, United States
- Continent
- Americas
- Country
- United States
- City
- Thornton
- Population
- 133.5K
- Elevation
- 1,631 m
- Coordinates
- 39.87°, -104.97°
Seasonal Breakdown
Spring
Mar–May
Avg High 16°C
Avg Low 0°C
Rain 10 days/mo
Summer
Jun–Aug
Avg High 29°C
Avg Low 14°C
Rain 8 days/mo
3/3 best months
Autumn
Sep–Nov
Avg High 19°C
Avg Low 4°C
Rain 5 days/mo
1/3 best months
Winter
Dec–Feb
Avg High 6°C
Avg Low -9°C
Rain 5 days/mo
Climate Charts
Based on historical averages (2016–2025)
Monthly Temperatures
HighLowShaded bands show the typical range across the available yearly records.
Line chart showing monthly temperatures. Jan: 4°C / -10°C . Feb: 7°C / -9°C . Mar: 12°C / -4°C . Apr: 16°C / 0°C . May: 20°C / 5°C . Jun: 28°C / 12°C . Jul: 31°C / 15°C . Aug: 30°C / 14°C . Sep: 27°C / 11°C . Oct: 19°C / 3°C . Nov: 12°C / -3°C . Dec: 7°C / -7°C .
Monthly Rainfall
Rainfall
Bar chart showing monthly rainfall. Jan: 25 mm. Feb: 31 mm. Mar: 55 mm. Apr: 53 mm. May: 97 mm. Jun: 51 mm. Jul: 39 mm. Aug: 38 mm. Sep: 29 mm. Oct: 28 mm. Nov: 26 mm. Dec: 18 mm.
Monthly Humidity
Humidity
Line chart showing monthly humidity. Jan: 65%. Feb: 60%. Mar: 58%. Apr: 53%. May: 60%. Jun: 51%. Jul: 48%. Aug: 49%. Sep: 46%. Oct: 50%. Nov: 56%. Dec: 56%.
Monthly Wind Speed
Wind SpeedGusts
Bar chart showing monthly wind speed. Jan: 13 km/h . Feb: 15 km/h . Mar: 16 km/h . Apr: 17 km/h . May: 17 km/h . Jun: 16 km/h . Jul: 15 km/h . Aug: 15 km/h . Sep: 15 km/h . Oct: 15 km/h . Nov: 14 km/h . Dec: 14 km/h .
Sunshine
Sunshine
Sunshine: Jan: 8h. Feb: 9h. Mar: 10h. Apr: 11h. May: 12h. Jun: 13h. Jul: 13h. Aug: 12h. Sep: 11h. Oct: 9h. Nov: 8h. Dec: 8h.
UV Index
UV Index
Bar chart showing monthly UV index. Jan: UV 3. Feb: UV 4. Mar: UV 6. Apr: UV 7. May: UV 8. Jun: UV 8. Jul: UV 8. Aug: UV 8. Sep: UV 7. Oct: UV 5. Nov: UV 3. Dec: UV 3.
Monthly Daylight Hours
Daylight12h reference
Monthly Dew Point & Comfort
Dew Point Dry Comfortable Humid Muggy Oppressive
Snow Days
Snow DaysSnowfall
Snow Days: Jan: 9 days. Feb: 9 days. Mar: 9 days. Apr: 7 days. May: 2 days. Jun: 0 days. Jul: 0 days. Aug: 0 days. Sep: 0 days. Oct: 3 days. Nov: 5 days. Dec: 6 days.
Climate Trends
Average highs have warmed by 0.8°C (1.4°F) across the available records. Average rainfall has remained broadly steady.
2016 to 2025
Avg high Avg rainfall
Climate summary
| Last 12 months | All years | |
|---|---|---|
| Hottest month | Jul 2025 · 31°C | Jul · 31°C |
| Coldest month | Jan 2025 · -14°C | Jan · -10°C |
| Wettest month | May 2025 · 84 mm | May · 97 mm |
| Windiest month | Apr 2025 · 17 km/h | Apr · 17 km/h |
Month-by-Month Weather Table
January
Poor 
February
Poor March
Poor April
Poor May
Fair June best
Excellent July best
Excellent August best
Excellent September best
Excellent October
Fair November
Poor December
Poor | Month | Temp | Feels Like | Rain | Sun | Humidity | UV | Status | Details |
|---|---|---|---|---|---|---|---|---|
| January | 4°C / -10°C | 0°C / -15°C | 5days (25 mm) Good | 7.7h Good | 65% Muggy | 3.1 Moderate | Poor | View Details |
| February | 7°C / -9°C | 3°C / -14°C | 6days (31 mm) Good | 9h Good | 60% Moderate | 4.3 Moderate | Poor | View Details |
| March | 12°C / -4°C | 8°C / -9°C | 9days (55 mm) Wet | 10h Excellent | 58% Moderate | 5.8 High | Poor | View Details |
| April | 16°C / 0°C | 13°C / -4°C | 9days (53 mm) Wet | 11h Excellent | 53% Moderate | 6.9 High | Poor | View Details |
| May | 20°C / 5°C | 18°C / 2°C | 13days (97 mm) Wet | 11.6h Excellent | 60% Moderate | 7.7 Very High | Fair | View Details |
| June best | 28°C / 12°C | 27°C / 10°C | 9days (51 mm) Wet | 13h Excellent | 51% Moderate | 8.2 Very High | Excellent | View Details |
| July best | 31°C / 15°C | 30°C / 14°C | 8days (39 mm) Wet | 13h Excellent | 48% Moderate | 8.4 Very High | Excellent | View Details |
| August best | 30°C / 14°C | 29°C / 13°C | 8days (38 mm) Wet | 11.9h Excellent | 49% Moderate | 7.8 Very High | Excellent | View Details |
| September best | 27°C / 11°C | 25°C / 8°C | 5days (29 mm) Good | 10.9h Excellent | 46% Moderate | 6.6 High | Excellent | View Details |
| October | 19°C / 3°C | 16°C / 0°C | 5days (28 mm) Good | 9.4h Good | 50% Moderate | 5.1 High | Fair | View Details |
| November | 12°C / -3°C | 8°C / -7°C | 5days (26 mm) Good | 8.2h Good | 56% Moderate | 3.4 Moderate | Poor | View Details |
| December | 7°C / -7°C | 3°C / -11°C | 4days (18 mm) Good | 7.6h Good | 56% Moderate | 2.8 Moderate | Poor | View Details |
Compare Nearby City Climates
Frequently Asked Questions
The best months to visit Thornton are June, July, August, September, when temperatures are comfortable and rainfall is at its lowest. This is based on 10-year climate averages for Thornton, scoring temperature, rainfall, humidity, and sunshine hours.
The hottest month in Thornton is July, with average daytime highs of 31°C (87°F). Plan outdoor activities for early morning or late afternoon if visiting during this period.
The coldest month in Thornton is January, with average overnight lows of -10°C (14°F). Pack warm layers and expect shorter daylight hours during this period.
The wettest month in Thornton is May, averaging 97mm of precipitation across 13 rainy days. An umbrella or waterproof jacket is essential.
Thornton receives approximately 123 sunshine hours per year. The sunniest month is June with around 13 hours. Based on climate data for Thornton.
The least favorable months to visit Thornton are January, February, March, December, primarily due to very cold temperatures. For the best conditions, consider June, July, August, September instead.
The annual average UV index in Thornton is 6, classified as high. Standard sun protection (sunscreen, hat) is recommended during prolonged outdoor exposure.
Average humidity in Thornton is 54%, classified as moderate. Humidity levels are generally comfortable and should not affect outdoor activities for most people.
Yes, Thornton receives snow. Months with snowfall average 6 snow days and 14 cm (6 in) of accumulation, with about 20 frost days during winter.
Average wind speeds in Thornton are 15 km/h (9 mph). The windiest month is April with peak winds reaching 17 km/h (11 mph) (gusts up to 37 km/h / 23 mph).
Thornton averages 8 clear-sky days per month with overall cloud cover around 43%. The clearest skies occur in October.
The annual average dew point in Thornton is 1°C (34°F), which feels dry and comfortable. Outdoor activities are comfortable year-round from a humidity standpoint.
Thornton has a Hot-Summer Continental climate, classified as Dfa under the Köppen system. Continental climates experience extreme temperature ranges — hot summers and cold, snowy winters.
The 'feels like' temperature in Thornton ranges from -1°C (30°F) to 15°C (59°F) on average. Wind chill makes winters feel noticeably colder than the actual temperature — layered clothing is recommended.
Yes, June is a great time to visit Thornton. It earns a climate score of 8.6/10 with Excellent.
For June in Thornton, pack Warm evening layer, Umbrella, Breathable clothing, Sunscreen (SPF 30+), Sun hat. With average highs of 28°C (82°F) and 9 rainy days, these essentials will keep you comfortable.
Data Source
Climate data derived from ERA5 reanalysis (ECMWF), averaged over 2016–2025. Sea surface temperature from marine reanalysis data. Climate scores and seasonal estimates are computed by WorldStats.
Last updated: