Hermiston climate — normals and trends
Hermiston (United States) has a hot-summer mediterranean climate (Csa) under the Köppen-Geiger classification. Its mean annual temperature is 12.6 °C and it receives 306 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 (24.9 °C on average) and the coldest is January (1.5 °C). Rainfall peaks in December.
Hermiston averages 63 frost days, 61 hot days (≥ 30 °C) and 75 rainy days per year.
Hermiston has warmed by +1.5 °C between 1940 and 2025, or +0.17 °C per decade. This trend is statistically significant.
The hottest day of the period reached 47.2 °C (on 29 June 2021) and the coldest -27.9 °C (on 31 January 1950).
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
HermistonOregon
- coords
- 45.84°, -119.29°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
12.6°C
Average daily high
18.2°C
Average daily low
7.3°C
Annual rainfall
306mm
Sunshine / day
10.0h
Mean relative humidity
56%
Average peak wind
17.8km/h
Seasonal range
23.4°C
Frost days (< 0 °C)
63 d/yr
Hot days (≥ 30 °C)
61 d/yr
Rainy days (≥ 1 mm)
75 d/yr
Annual snowfall
21.6 cm
Average feels-like high
15.2 °C
Average feels-like low
4.1 °C
Average peak gust
35.5 km/h
Tropical nights (≥ 20 °C)
16 d/yr
Solar radiation
16.2 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.5 °C
since 1940
+0.2 °C per decade · r² = 0.27 · 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
47.2 °C
29 June 2021
Coldest day
-27.9 °C
31 January 1950
Wettest day
33 mm
18 November 1996
Windiest day
61.1 km/h
8 January 1990
Strongest gust
110.9 km/h
30 October 1997
Hottest feels-like
46.8 °C
29 June 2021
Coldest feels-like
-32.6 °C
31 January 1950
Snowiest day
12.6 cm
26 January 1969
Sunniest day
15.5 h
18 June 2025
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 | 5.3 °C | +0.4 °C | 34 mm | -9 mm |
| Feb | 6.4 °C | -2.3 °C | 56 mm | +25 mm |
| Mar | 14.9 °C | +1.6 °C | 43 mm | +9 mm |
| Apr | 19.8 °C | +2.0 °C | 15 mm | -12 mm |
| May | 24.1 °C | +1.1 °C | 10 mm | -15 mm |
| Jun | 30.0 °C | +2.7 °C | 1 mm | -14 mm |
| Jul | 33.9 °C | +1.6 °C | 4 mm | -0 mm |
| Aug | 33.1 °C | +2.0 °C | 3 mm | -3 mm |
| Sep | 29.5 °C | +3.5 °C | 8 mm | -4 mm |
| Oct | 17.5 °C | -0.7 °C | 26 mm | -0 mm |
| Nov | 11.5 °C | +1.6 °C | 32 mm | -8 mm |
| Dec | 10.3 °C | +4.8 °C | 69 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 Hermiston?
Hermiston has a hot-summer mediterranean climate (Köppen Csa). Over 1940-2025, the average annual temperature is 12.6 °C and it receives 306 mm of precipitation per year.
What is the hottest day ever recorded in Hermiston?
The hottest day measured in Hermiston between 1940 and 2025 was 29 June 2021, reaching 47.2 °C.
What is the coldest day in Hermiston?
The coldest day measured in Hermiston between 1940 and 2025 was 31 January 1950, at -27.9 °C.
Does it snow in Hermiston?
Yes. Hermiston gets on average 21.6 cm of snow per year and has around 63 frost days.
Has the climate of Hermiston warmed?
Yes: Hermiston warmed by +1.5 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Hermiston?
The wettest day measured in Hermiston between 1940 and 2025 was 18 November 1996, with 33 mm of rain in 24 hours.
What was the windiest day in Hermiston?
The windiest day measured in Hermiston between 1940 and 2025 was 8 January 1990, with winds reaching 61.1 km/h.
What is the warmest month in Hermiston?
The warmest month in Hermiston is July (24.9 °C on average); the coldest is January (1.5 °C).
How much does it rain in Hermiston?
Hermiston receives on average 306 mm of precipitation per year, spread over about 75 rainy days.
Is it sunny in Hermiston?
Hermiston gets on average 10.0 hours of sunshine per day, roughly 3,650 hours per year over 1940-2025.
What is the biggest single-day snowfall in Hermiston?
The heaviest 24-hour snowfall measured in Hermiston between 1940 and 2025 was 26 January 1969, with 12.6 cm.
Are there tropical nights in Hermiston?
Yes: Hermiston has on average 16 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Hermiston?
In Hermiston, between 1940 and 2025, the highest apparent temperature reached 46.8 °C on 29 June 2021, and the lowest was -32.6 °C on 31 January 1950.
Compare Hermiston with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Hermiston