Longmont climate — normals and trends
Longmont (United States) has a hot-summer humid continental climate (Dfa) under the Köppen-Geiger classification. Its mean annual temperature is 9.0 °C and it receives 534 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (22.2 °C on average) and the coldest is January (-3.3 °C). Rainfall peaks in May.
Longmont averages 151 frost days, 42 hot days (≥ 30 °C) and 92 rainy days per year.
Longmont has warmed by +2.6 °C between 1940 and 2025, or +0.30 °C per decade. This trend is statistically significant.
The number of frost days there went from about 166 to 136 per year over the period.
The hottest day of the period reached 38.9 °C (on 23 June 1954) and the coldest -35.8 °C (on 12 January 1963).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
LongmontColorado
- coords
- 40.17°, -105.10°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.0°C
Average daily high
16.4°C
Average daily low
2.4°C
Annual rainfall
534mm
Sunshine / day
10.5h
Mean relative humidity
59%
Average peak wind
13.2km/h
Seasonal range
25.5°C
Frost days (< 0 °C)
151 d/yr
Hot days (≥ 30 °C)
42 d/yr
Rainy days (≥ 1 mm)
92 d/yr
Annual snowfall
109.4 cm
Average feels-like high
14.0 °C
Average feels-like low
-0.5 °C
Average peak gust
29.6 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
18.1 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.6 °C
since 1940
+0.3 °C per decade · r² = 0.46 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
38.9 °C
23 June 1954
Coldest day
-35.8 °C
12 January 1963
Wettest day
78 mm
8 June 1974
Windiest day
51.1 km/h
10 October 1949
Strongest gust
106.9 km/h
2 April 1982
Hottest feels-like
38.9 °C
18 July 2022
Coldest feels-like
-40.9 °C
12 January 1963
Snowiest day
34.5 cm
18 March 2003
Sunniest day
14.2 h
29 June 1941
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 2.7 °C | -1.0 °C | 30 mm | +8 mm |
| Feb | 5.6 °C | -0.2 °C | 30 mm | +7 mm |
| Mar | 15.8 °C | +5.6 °C | 37 mm | -9 mm |
| Apr | 17.2 °C | +1.9 °C | 50 mm | -20 mm |
| May | 21.2 °C | +0.9 °C | 104 mm | +8 mm |
| Jun | 27.6 °C | +1.3 °C | 75 mm | +13 mm |
| Jul | 31.2 °C | +1.3 °C | 49 mm | +6 mm |
| Aug | 29.7 °C | +0.9 °C | 83 mm | +42 mm |
| Sep | 25.3 °C | +0.8 °C | 58 mm | +17 mm |
| Oct | 18.9 °C | +1.1 °C | 22 mm | -17 mm |
| Nov | 14.6 °C | +5.0 °C | 8 mm | -22 mm |
| Dec | 12.5 °C | +7.7 °C | 16 mm | -6 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Longmont?
Longmont has a hot-summer humid continental climate (Köppen Dfa). Over 1940-2025, the average annual temperature is 9.0 °C and it receives 534 mm of precipitation per year.
What is the hottest day ever recorded in Longmont?
The hottest day measured in Longmont between 1940 and 2025 was 23 June 1954, reaching 38.9 °C.
What is the coldest day in Longmont?
The coldest day measured in Longmont between 1940 and 2025 was 12 January 1963, at -35.8 °C.
Does it snow in Longmont?
Yes. Longmont gets on average 109.4 cm of snow per year and has around 151 frost days.
Has the climate of Longmont warmed?
Yes: Longmont warmed by +2.6 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Longmont?
The wettest day measured in Longmont between 1940 and 2025 was 8 June 1974, with 78 mm of rain in 24 hours.
What was the windiest day in Longmont?
The windiest day measured in Longmont between 1940 and 2025 was 10 October 1949, with winds reaching 51.1 km/h.
What is the warmest month in Longmont?
The warmest month in Longmont is July (22.2 °C on average); the coldest is January (-3.3 °C).
How much does it rain in Longmont?
Longmont receives on average 534 mm of precipitation per year, spread over about 92 rainy days.
Is it sunny in Longmont?
Longmont gets on average 10.5 hours of sunshine per day, roughly 3,833 hours per year over 1940-2025.
What is the biggest single-day snowfall in Longmont?
The heaviest 24-hour snowfall measured in Longmont between 1940 and 2025 was 18 March 2003, with 34.5 cm.
Are there tropical nights in Longmont?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Longmont.
What was the most extreme apparent temperature in Longmont?
In Longmont, between 1940 and 2025, the highest apparent temperature reached 38.9 °C on 18 July 2022, and the lowest was -40.9 °C on 12 January 1963.
Compare Longmont with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Longmont