Lewiston climate — normals and trends
Lewiston (United States) has a hot-summer mediterranean continental climate (Dsa) under the Köppen-Geiger classification. Its mean annual temperature is 9.8 °C and it receives 550 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 (22.5 °C on average) and the coldest is January (-1.8 °C). Rainfall peaks in December.
Lewiston averages 109 frost days, 36 hot days (≥ 30 °C) and 107 rainy days per year.
Lewiston has warmed by +2.5 °C between 1940 and 2025, or +0.29 °C per decade. This trend is statistically significant.
The number of frost days there went from about 126 to 92 per year over the period.
The hottest day of the period reached 43.1 °C (on 4 August 1961) and the coldest -31.2 °C (on 26 January 1957).
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
LewistonIdaho
- coords
- 46.42°, -117.02°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.8°C
Average daily high
15.1°C
Average daily low
4.5°C
Annual rainfall
550mm
Sunshine / day
9.7h
Mean relative humidity
64%
Average peak wind
13.4km/h
Seasonal range
24.3°C
Frost days (< 0 °C)
109 d/yr
Hot days (≥ 30 °C)
36 d/yr
Rainy days (≥ 1 mm)
107 d/yr
Annual snowfall
71.3 cm
Average feels-like high
12.8 °C
Average feels-like low
1.6 °C
Average peak gust
30.6 km/h
Tropical nights (≥ 20 °C)
4 d/yr
Solar radiation
15.5 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.5 °C
since 1940
+0.3 °C per decade · r² = 0.51 · 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
43.1 °C
4 August 1961
Coldest day
-31.2 °C
26 January 1957
Wettest day
38 mm
24 November 1964
Windiest day
44.3 km/h
17 December 2025
Strongest gust
112.0 km/h
16 November 2010
Hottest feels-like
42.9 °C
29 June 2021
Coldest feels-like
-36.7 °C
5 January 1942
Snowiest day
15.2 cm
20 January 1943
Sunniest day
15.6 h
25 June 2022
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 | 4.1 °C | +2.4 °C | 46 mm | -21 mm |
| Feb | 2.1 °C | -3.1 °C | 91 mm | +37 mm |
| Mar | 12.7 °C | +2.6 °C | 79 mm | +19 mm |
| Apr | 16.4 °C | +1.7 °C | 22 mm | -31 mm |
| May | 20.8 °C | +1.7 °C | 26 mm | -23 mm |
| Jun | 26.1 °C | +2.9 °C | 4 mm | -31 mm |
| Jul | 31.1 °C | +2.0 °C | 1 mm | -9 mm |
| Aug | 30.4 °C | +1.7 °C | 26 mm | +12 mm |
| Sep | 27.5 °C | +3.9 °C | 26 mm | +2 mm |
| Oct | 15.8 °C | -0.2 °C | 38 mm | -7 mm |
| Nov | 9.9 °C | +2.6 °C | 55 mm | -13 mm |
| Dec | 7.8 °C | +5.4 °C | 133 mm | +63 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 Lewiston?
Lewiston has a hot-summer mediterranean continental climate (Köppen Dsa). Over 1940-2025, the average annual temperature is 9.8 °C and it receives 550 mm of precipitation per year.
What is the hottest day ever recorded in Lewiston?
The hottest day measured in Lewiston between 1940 and 2025 was 4 August 1961, reaching 43.1 °C.
What is the coldest day in Lewiston?
The coldest day measured in Lewiston between 1940 and 2025 was 26 January 1957, at -31.2 °C.
Does it snow in Lewiston?
Yes. Lewiston gets on average 71.3 cm of snow per year and has around 109 frost days.
Has the climate of Lewiston warmed?
Yes: Lewiston warmed by +2.5 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Lewiston?
The wettest day measured in Lewiston between 1940 and 2025 was 24 November 1964, with 38 mm of rain in 24 hours.
What was the windiest day in Lewiston?
The windiest day measured in Lewiston between 1940 and 2025 was 17 December 2025, with winds reaching 44.3 km/h.
What is the warmest month in Lewiston?
The warmest month in Lewiston is July (22.5 °C on average); the coldest is January (-1.8 °C).
How much does it rain in Lewiston?
Lewiston receives on average 550 mm of precipitation per year, spread over about 107 rainy days.
Is it sunny in Lewiston?
Lewiston gets on average 9.7 hours of sunshine per day, roughly 3,540 hours per year over 1940-2025.
What is the biggest single-day snowfall in Lewiston?
The heaviest 24-hour snowfall measured in Lewiston between 1940 and 2025 was 20 January 1943, with 15.2 cm.
Are there tropical nights in Lewiston?
Yes: Lewiston has on average 4 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Lewiston?
In Lewiston, between 1940 and 2025, the highest apparent temperature reached 42.9 °C on 29 June 2021, and the lowest was -36.7 °C on 5 January 1942.
Compare Lewiston with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Lewiston