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Eureka, California climate
Csb Warm-summer Mediterranean
Eureka has a mildly seasonal cool-temperate climate (Warm-summer Mediterranean, Köppen Csb). The hottest month is August with an average daily high near 64°F, while the coldest is December averaging around 40°F at night. Precipitation totals about 40 inches a year and is strongly seasonal — December alone averages 8.1 inches while July barely receives 0.18 inches.
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figuresClear vs cloudy days
Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day countsEureka climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 55 | 55 | 56 | 57 | 60 | 62 | 63 | 64 | 64 | 62 | 58 | 55 |
| Avg temp (°F) | 48 | 48 | 49 | 51 | 54 | 56 | 58 | 59 | 57 | 54 | 51 | 47 |
| Avg low (°F) | 41 | 41 | 42 | 44 | 48 | 50 | 52 | 53 | 51 | 47 | 43 | 40 |
| Precipitation (in) | 6.7 | 5.6 | 5.8 | 3.6 | 1.7 | 0.7 | 0.2 | 0.2 | 0.7 | 2.3 | 4.9 | 8.1 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°F) | 55 | 55 | 56 | 57 | 60 | 62 |
| Avg temp (°F) | 48 | 48 | 49 | 51 | 54 | 56 |
| Avg low (°F) | 41 | 41 | 42 | 44 | 48 | 50 |
| Precipitation (in) | 6.7 | 5.6 | 5.8 | 3.6 | 1.7 | 0.7 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°F) | 63 | 64 | 64 | 62 | 58 | 55 |
| Avg temp (°F) | 58 | 59 | 57 | 54 | 51 | 47 |
| Avg low (°F) | 52 | 53 | 51 | 47 | 43 | 40 |
| Precipitation (in) | 0.2 | 0.2 | 0.7 | 2.3 | 4.9 | 8.1 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 17 | 15 | 16 | 14 | 9 | 6 | 3 | 4 | 5 | 9 | 14 | 17 |
| Days with low ≤ 32°F (days) | 2 | 1 | 0.6 | 0.1 | — | — | — | — | — | — | 0.9 | 3 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 17 | 15 | 16 | 14 | 9 | 6 |
| Days with low ≤ 32°F (days) | 2 | 1 | 0.6 | 0.1 | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 3 | 4 | 5 | 9 | 14 | 17 |
| Days with low ≤ 32°F (days) | — | — | — | — | 0.9 | 3 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 74 | 75 | 75 | 72 | 68 | 60 | 59 | 60 | 57 | 59 | 68 | 73 |
| Clear days (≤ 30% cloud) | 3 | 3 | 2 | 3 | 4 | 5 | 5 | 6 | 6 | 6 | 4 | 4 |
| Partly cloudy days (30–70%) | 7 | 6 | 8 | 8 | 10 | 12 | 13 | 12 | 13 | 12 | 9 | 7 |
| Cloudy days (≥ 70%) | 21 | 19 | 21 | 19 | 17 | 12 | 12 | 14 | 11 | 13 | 17 | 20 |
| Relative humidity (%) | 83 | 83 | 84 | 85 | 88 | 89 | 89 | 88 | 84 | 83 | 83 | 82 |
| Wind speed (mph) | 9.7 | 9.8 | 10.0 | 9.4 | 9.5 | 10.2 | 9.4 | 8.3 | 7.6 | 7.8 | 8.6 | 10.3 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 74 | 75 | 75 | 72 | 68 | 60 |
| Clear days (≤ 30% cloud) | 3 | 3 | 2 | 3 | 4 | 5 |
| Partly cloudy days (30–70%) | 7 | 6 | 8 | 8 | 10 | 12 |
| Cloudy days (≥ 70%) | 21 | 19 | 21 | 19 | 17 | 12 |
| Relative humidity (%) | 83 | 83 | 84 | 85 | 88 | 89 |
| Wind speed (mph) | 9.7 | 9.8 | 10.0 | 9.4 | 9.5 | 10.2 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 59 | 60 | 57 | 59 | 68 | 73 |
| Clear days (≤ 30% cloud) | 5 | 6 | 6 | 6 | 4 | 4 |
| Partly cloudy days (30–70%) | 13 | 12 | 13 | 12 | 9 | 7 |
| Cloudy days (≥ 70%) | 12 | 14 | 11 | 13 | 17 | 20 |
| Relative humidity (%) | 89 | 88 | 84 | 83 | 83 | 82 |
| Wind speed (mph) | 9.4 | 8.3 | 7.6 | 7.8 | 8.6 | 10.3 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Eureka Wfo Woodley IS (NOAA GHCN station USW00024213), inside the city.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.