Helena climate — normals and trends
Helena (United States) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 4.3 °C and it receives 559 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 (17.9 °C on average) and the coldest is January (-8.0 °C). Rainfall peaks in June.
Helena averages 190 frost days, 10 hot days (≥ 30 °C) and 117 rainy days per year.
Helena has warmed by +2.1 °C between 1940 and 2025, or +0.24 °C per decade. This trend is statistically significant.
The number of frost days there went from about 201 to 179 per year over the period.
The hottest day of the period reached 36.6 °C (on 5 August 1961) and the coldest -39.7 °C (on 13 January 2024).
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
HelenaMontana
- coords
- 46.59°, -112.04°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
4.3°C
Average daily high
10.3°C
Average daily low
-1.4°C
Annual rainfall
559mm
Sunshine / day
10.1h
Mean relative humidity
65%
Average peak wind
13.1km/h
Seasonal range
25.9°C
Frost days (< 0 °C)
190 d/yr
Hot days (≥ 30 °C)
10 d/yr
Rainy days (≥ 1 mm)
117 d/yr
Annual snowfall
152.8 cm
Average feels-like high
7.2 °C
Average feels-like low
-4.9 °C
Average peak gust
37.2 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
16.1 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.1 °C
since 1940
+0.2 °C per decade · r² = 0.34 · 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
36.6 °C
5 August 1961
Coldest day
-39.7 °C
13 January 2024
Wettest day
62 mm
13 June 2017
Windiest day
39.6 km/h
17 December 2025
Strongest gust
106.9 km/h
17 December 2025
Hottest feels-like
35.8 °C
12 July 2002
Coldest feels-like
-45.3 °C
13 January 2024
Snowiest day
30.5 cm
28 May 1982
Sunniest day
15.0 h
21 May 1940
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 | -4.0 °C | -0.5 °C | 29 mm | +1 mm |
| Feb | -5.2 °C | -4.3 °C | 51 mm | +25 mm |
| Mar | 6.0 °C | +2.9 °C | 41 mm | +1 mm |
| Apr | 10.3 °C | +1.5 °C | 40 mm | -17 mm |
| May | 17.2 °C | +2.6 °C | 101 mm | +15 mm |
| Jun | 21.1 °C | +1.5 °C | 68 mm | -24 mm |
| Jul | 25.8 °C | +0.2 °C | 50 mm | +5 mm |
| Aug | 25.3 °C | +0.3 °C | 48 mm | +7 mm |
| Sep | 23.4 °C | +4.5 °C | 14 mm | -33 mm |
| Oct | 10.9 °C | -0.6 °C | 48 mm | +11 mm |
| Nov | 7.0 °C | +4.3 °C | 34 mm | +2 mm |
| Dec | 2.8 °C | +5.2 °C | 54 mm | +26 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 Helena?
Helena has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 4.3 °C and it receives 559 mm of precipitation per year.
What is the hottest day ever recorded in Helena?
The hottest day measured in Helena between 1940 and 2025 was 5 August 1961, reaching 36.6 °C.
What is the coldest day in Helena?
The coldest day measured in Helena between 1940 and 2025 was 13 January 2024, at -39.7 °C.
Does it snow in Helena?
Yes. Helena gets on average 152.8 cm of snow per year and has around 190 frost days.
Has the climate of Helena warmed?
Yes: Helena warmed by +2.1 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Helena?
The wettest day measured in Helena between 1940 and 2025 was 13 June 2017, with 62 mm of rain in 24 hours.
What was the windiest day in Helena?
The windiest day measured in Helena between 1940 and 2025 was 17 December 2025, with winds reaching 39.6 km/h.
What is the warmest month in Helena?
The warmest month in Helena is July (17.9 °C on average); the coldest is January (-8.0 °C).
How much does it rain in Helena?
Helena receives on average 559 mm of precipitation per year, spread over about 117 rainy days.
Is it sunny in Helena?
Helena gets on average 10.1 hours of sunshine per day, roughly 3,687 hours per year over 1940-2025.
What is the biggest single-day snowfall in Helena?
The heaviest 24-hour snowfall measured in Helena between 1940 and 2025 was 28 May 1982, with 30.5 cm.
Are there tropical nights in Helena?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Helena.
What was the most extreme apparent temperature in Helena?
In Helena, between 1940 and 2025, the highest apparent temperature reached 35.8 °C on 12 July 2002, and the lowest was -45.3 °C on 13 January 2024.
Compare Helena with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Helena