Eureka, United States experiences average highs of 16°C (61°F) and lows of 10°C (50°F) throughout the year. Rainfall is moderate, averaging about 9 rainy days per month. Sunshine is abundant, averaging about 10 hours per day. Average highs have stayed broadly stable across the available records.
Eureka, United States Weather & Climate 2026
Monthly climate averages for Eureka, United States. Based on 10-year ERA5 reanalysis data.
Climate Overview
Drier season: May–Oct 
Wetter season: Jan–Dec At-a-Glance Climate Summary
Live Weather & Air Quality
Key figures
Climate Score
6.6/10
Best: June, July, August, September
UV Index
5
Low
Temperature 16°C / 10°C
Feels Like 15°C / 8°C
Rainy Days 9
Rainfall 111 mm
Sunshine 10 h
Humidity 83%
Wind Speed 17 km/h
Dew Point 10°C
Snow Days 3 days
Hottest Month
20°C
August
Avg Low13°C
Rain1days
Coldest Month
7°C
February
Avg High12°C
Rain13days
Driest Month
1days
July
Avg High19°C
Avg Low13°C
Windiest Month
19 km/h
March (Gusts 43)
Sea Temperature
11°C – 15°C
Warmest water: September (
14.7°C
)
Worst Time to Visit
Consider avoiding January, February, March, December due to heavy rainfall.
Sun Position
Sunrise 05:46
Daylight 15.1h
Sunset 20:51
Live conditions—
Eureka on the map · live conditions
Eureka, United States
- Continent
- Americas
- Country
- United States
- City
- Eureka
- Population
- 27K
- Elevation
- 12 m
- Coordinates
- 40.80°, -124.16°
Seasonal Breakdown
Spring
Mar–May
Avg High 14°C
Avg Low 8°C
Rain 11 days/mo
Summer
Jun–Aug
Avg High 19°C
Avg Low 12°C
Rain 1 days/mo
3/3 best months
Autumn
Sep–Nov
Avg High 17°C
Avg Low 11°C
Rain 7 days/mo
1/3 best months
Winter
Dec–Feb
Avg High 13°C
Avg Low 7°C
Rain 15 days/mo
Climate Charts
Based on historical averages (2016–2025)
Monthly Temperatures
HighLowShaded bands show the typical range across the available yearly records.
Line chart showing monthly temperatures. Jan: 13°C / 7°C . Feb: 12°C / 7°C . Mar: 13°C / 7°C . Apr: 14°C / 8°C . May: 15°C / 9°C . Jun: 17°C / 11°C . Jul: 19°C / 13°C . Aug: 20°C / 13°C . Sep: 20°C / 13°C . Oct: 18°C / 11°C . Nov: 15°C / 9°C . Dec: 13°C / 7°C .
Monthly Rainfall
Rainfall
Bar chart showing monthly rainfall. Jan: 254 mm. Feb: 186 mm. Mar: 210 mm. Apr: 100 mm. May: 53 mm. Jun: 15 mm. Jul: 4 mm. Aug: 5 mm. Sep: 24 mm. Oct: 86 mm. Nov: 174 mm. Dec: 216 mm.
Monthly Humidity
Humidity
Line chart showing monthly humidity. Jan: 83%. Feb: 83%. Mar: 83%. Apr: 83%. May: 84%. Jun: 83%. Jul: 82%. Aug: 82%. Sep: 82%. Oct: 81%. Nov: 83%. Dec: 84%.
Monthly Wind Speed
Wind SpeedGusts
Bar chart showing monthly wind speed. Jan: 19 km/h . Feb: 19 km/h . Mar: 19 km/h . Apr: 18 km/h . May: 18 km/h . Jun: 17 km/h . Jul: 15 km/h . Aug: 14 km/h . Sep: 14 km/h . Oct: 15 km/h . Nov: 16 km/h . Dec: 17 km/h .
Sunshine
Sunshine
Sunshine: Jan: 6h. Feb: 7h. Mar: 8h. Apr: 10h. May: 12h. Jun: 13h. Jul: 13h. Aug: 13h. Sep: 11h. Oct: 9h. Nov: 7h. Dec: 5h.
Sea Temperature
Sea Temperatureswim
Line chart showing monthly sea temperature. Jan: 11°C . Feb: 11°C . Mar: 11°C . Apr: 12°C . May: 12°C . Jun: 12°C . Jul: 14°C . Aug: 15°C . Sep: 15°C . Oct: 13°C . Nov: 12°C . Dec: 11°C .
UV Index
UV Index
Bar chart showing monthly UV index. Jan: UV 2. Feb: UV 3. Mar: UV 4. Apr: UV 6. May: UV 7. Jun: UV 8. Jul: UV 8. Aug: UV 7. Sep: UV 6. Oct: UV 4. Nov: UV 3. Dec: UV 2.
Monthly Daylight Hours
Daylight12h reference
Monthly Dew Point & Comfort
Dew Point Dry Comfortable Humid Muggy Oppressive
Snow Days
Snow DaysSnowfall
Snow Days: Jan: 2 days. Feb: 5 days. Mar: 5 days. Apr: 1 days. May: 0 days. Jun: 0 days. Jul: 0 days. Aug: 0 days. Sep: 0 days. Oct: 0 days. Nov: 1 days. Dec: 2 days.
Climate Trends
Average highs have stayed broadly stable across the available records. Average rainfall is trending drier by about 13 mm.
2016 to 2025
Avg high Avg rainfall
Climate summary
| Last 12 months | All years | |
|---|---|---|
| Hottest month | Aug 2025 · 20°C | Aug · 20°C |
| Coldest month | Jan 2025 · 6°C | Feb · 7°C |
| Wettest month | Dec 2025 · 307 mm | Jan · 254 mm |
| Windiest month | Mar 2025 · 20 km/h | Mar · 19 km/h |
Month-by-Month Weather Table
January
Wet 
February
Wet March
Wet April
Fair May
Good June best
Excellent July best
Excellent August best
Excellent September best
Excellent October
Good November
Fair December
Wet | Month | Temp | Feels Like | Rain | Sun | Humidity | UV | Status | Details |
|---|---|---|---|---|---|---|---|---|
| January | 13°C / 7°C | 11°C / 4°C | 17days (254 mm) Wet | 5.7h Fair | 83% Humid | 2.3 Moderate | Wet | View Details |
| February | 12°C / 7°C | 10°C / 4°C | 13days (186 mm) Wet | 7.2h Good | 83% Humid | 3.1 Moderate | Wet | View Details |
| March | 13°C / 7°C | 10°C / 4°C | 16days (210 mm) Wet | 8.3h Good | 83% Humid | 4.1 Moderate | Wet | View Details |
| April | 14°C / 8°C | 12°C / 6°C | 10days (100 mm) Wet | 10.3h Excellent | 83% Humid | 6 High | Fair | View Details |
| May | 15°C / 9°C | 15°C / 8°C | 7days (53 mm) Good | 12h Excellent | 84% Humid | 7.3 Very High | Good | View Details |
| June best | 17°C / 11°C | 17°C / 10°C | 2days (15 mm) Excellent | 13.2h Excellent | 83% Humid | 7.7 Very High | Excellent | View Details |
| July best | 19°C / 13°C | 20°C / 12°C | 1days (4 mm) Excellent | 13.4h Excellent | 82% Humid | 7.9 Very High | Excellent | View Details |
| August best | 20°C / 13°C | 21°C / 13°C | 1days (5 mm) Excellent | 12.6h Excellent | 82% Humid | 7.2 Very High | Excellent | View Details |
| September best | 20°C / 13°C | 20°C / 13°C | 3days (24 mm) Excellent | 11h Excellent | 82% Humid | 5.9 High | Excellent | View Details |
| October | 18°C / 11°C | 17°C / 10°C | 7days (86 mm) Good | 9.1h Good | 81% Humid | 4.3 Moderate | Good | View Details |
| November | 15°C / 9°C | 13°C / 6°C | 12days (174 mm) Wet | 7h Good | 83% Humid | 2.7 Moderate | Fair | View Details |
| December | 13°C / 7°C | 11°C / 5°C | 14days (216 mm) Wet | 5.4h Fair | 84% Humid | 1.9 Low | Wet | View Details |
Compare Nearby City Climates
Frequently Asked Questions
The best months to visit Eureka are June, July, August, September, when temperatures are comfortable and rainfall is at its lowest. This is based on 10-year climate averages for Eureka, scoring temperature, rainfall, humidity, and sunshine hours.
The hottest month in Eureka is August, with average daytime highs of 20°C (68°F). Plan outdoor activities for early morning or late afternoon if visiting during this period.
The coldest month in Eureka is February, with average overnight lows of 7°C (44°F). Pack warm layers and expect shorter daylight hours during this period.
The wettest month in Eureka is January, averaging 254mm of precipitation across 17 rainy days. An umbrella or waterproof jacket is essential.
The rainy season in Eureka runs through January, March, December, February, with the heaviest rainfall in January. Based on 10-year averages for Eureka.
Eureka receives approximately 115 sunshine hours per year. The sunniest month is July with around 13 hours. Based on climate data for Eureka.
The least favorable months to visit Eureka are January, February, March, December, primarily due to heavy rainfall. For the best conditions, consider June, July, August, September instead.
The annual average UV index in Eureka is 5, classified as moderate. Standard sun protection (sunscreen, hat) is recommended during prolonged outdoor exposure.
Average humidity in Eureka is 83%, classified as humid. High humidity makes warm temperatures feel significantly hotter — lightweight, breathable clothing is recommended.
Sea temperatures in Summer average 12°C (54°F), which most swimmers will find too cold without a wetsuit.
Yes, Eureka receives snow. Months with snowfall average 3 snow days and 6 cm (2 in) of accumulation, with about 0 frost days during winter.
Average wind speeds in Eureka are 17 km/h (11 mph). The windiest month is March with peak winds reaching 19 km/h (12 mph) (gusts up to 43 km/h / 27 mph).
Eureka averages 6 clear-sky days per month with overall cloud cover around 53%. The clearest skies occur in July.
The annual average dew point in Eureka is 10°C (50°F), which feels pleasant with low humidity. Outdoor activities are comfortable year-round from a humidity standpoint.
Eureka has a Warm-Summer Mediterranean climate, classified as Csb under the Köppen system. Temperate climates have mild winters and warm summers, with rainfall spread across the year and four distinct seasons.
The 'feels like' temperature in Eureka ranges from 8°C (46°F) to 15°C (59°F) on average. The 'feels like' temperature closely matches the actual temperature throughout most of the year.
Yes, June is a great time to visit Eureka. It earns a climate score of 8.1/10 with Excellent.
For June in Eureka, pack Layered clothing, Light jacket, Comfortable walking shoes. With average highs of 17°C (63°F) and 2 rainy days, these essentials will keep you comfortable.
Data Source
Climate data derived from ERA5 reanalysis (ECMWF), averaged over 2016–2025. Sea surface temperature from marine reanalysis data. Climate scores and seasonal estimates are computed by WorldStats.
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