Eureka in Summer
In summer (June, July and August), Eureka sees average daytime highs around 59°F and overnight lows near 53°F, with 1.2 in of rain over about 5 wet days across the season. It is the warmest season of the year and the driest season of the year.
Over the season highs climb from about 57°F in early June to 61°F by late August. The sky is clear or mostly clear about 49% of the time across summer, and the air most often feels dry.
Summer is Eureka's best season of the year to visit on our travel score. Eureka has little temperature swing across the year, so its calendar seasons blur — the season framing matters less here than for a place with four distinct seasons. For the whole year in context, see Eureka's year-round climate.
- Avg daytime high
- 59°F
- warmest season of the year
- Avg overnight low
- 53°F
- Rainfall
- 1.2 in
- 5 wet days
- Avg wind
- 9 mph
- Travel score
- 5.7
- best season of the year
- Months
- Jun · Jul · Aug
Temperature in Eureka in Summer
Over the season highs climb from about 57°F in early June to 61°F by late August.
A typical summer day in Eureka reaches about 59°F and drops to 53°F overnight. The warmest of the three months is August, the coolest June.
Eureka weather by month
How the three summer months (June, July and August) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 53° / 46° | 8.0 | 15.3 | 9.4 | 2.6 |
| Feb | 53° / 46° | 6.7 | 13.4 | 10.4 | 2.6 |
| Mar | 53° / 47° | 7.0 | 14.7 | 11.7 | 2.6 |
| Apr | 53° / 48° | 4.1 | 11.8 | 13.1 | 3.0 |
| May | 55° / 50° | 2.1 | 7 | 14.2 | 3.9 |
| Jun | 57° / 52° | 0.9 | 3.7 | 14.9 | 4.9 |
| Jul | 60° / 53° | 0.1 | 0.8 | 14.6 | 6.0 |
| Aug | 61° / 54° | 0.2 | 0.9 | 13.6 | 6.3 |
| Sep | 61° / 54° | 0.6 | 2.3 | 12.3 | 6.3 |
| Oct | 59° / 52° | 2.9 | 6.3 | 10.9 | 5.1 |
| Nov | 55° / 49° | 5.7 | 12.5 | 9.7 | 3.3 |
| Dec | 53° / 47° | 9.6 | 15.6 | 9.1 | 2.6 |
Cloud cover in Summer
The sky is clear or mostly clear about 49% of the time across summer.
Chance of precipitation in Summer
Eureka gets around 1.2 in of rain over 5 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 9 mph across summer.
Sunrise & sunset in Summer
Daylight runs from about 14 h 42 min in early June to 13 hours by late August. The lit band spans sunrise to sunset each day.
Solar energy in Summer
Average shortwave solar energy reaching the ground each day across summer, about 7.3 kWh/m².
Hazard calendar for Eureka
None of Eureka's seasonal hazards peak in summer. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do.
Eureka's rainy season runs November–March, when most of the year's rain falls.
Is summer a good time to visit Eureka?
Our two travel scores rate summer for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
summer is a reasonable time to visit Eureka for sightseeing.
What to pack for Eureka in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, Eureka sees daytime highs around 59°F and nights near 53°F. Pack sun protection. Worth having: a warm layer. About 5 days see rain.
Sea temperature near Eureka in Summer
The nearest coast averages about 54°F across summer — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea offshore is warmest in August at about 55°F and coldest in March near 51°F.
The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°F) | 52 | 52 | 51 | 52 | 52 | 53 | 54 | 55 | 55 | 54 | 53 | 53 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 52 | Bracing |
| Feb | 52 | Bracing |
| Mar | 51 | Bracing |
| Apr | 52 | Bracing |
| May | 52 | Bracing |
| Jun | 53 | Bracing |
| Jul | 54 | Bracing |
| Aug | 55 | Bracing |
| Sep | 55 | Bracing |
| Oct | 54 | Bracing |
| Nov | 53 | Bracing |
| Dec | 53 | Bracing |
UV index in Eureka in Summer
Clear-sky midday UV across summer averages around 9 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Eureka peaks around June 21 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 at about 2 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 2 | 3 | 5 | 6 | 9 | 10 | 9 | 8 | 5 | 5 | 2 | 2 |
| Level | Low | Moderate | Moderate | High | Very high | Very high | Very high | Very high | High | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 2 | Low |
| Feb | 3 | Moderate |
| Mar | 5 | Moderate |
| Apr | 6 | High |
| May | 9 | Very high |
| Jun | 10 | Very high |
| Jul | 9 | Very high |
| Aug | 8 | Very high |
| Sep | 5 | High |
| Oct | 5 | Moderate |
| Nov | 2 | Low |
| Dec | 2 | Low |
Air quality in Eureka in Summer
Average fine-particle pollution (PM2.5) through the year — so you can see where summer falls, not just the annual average.
Air quality in Eureka is worst in September — around 35 µg/m³ PM2.5 (poor), about 6.3× the cleanest month (December, 6 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 6 | 7 | 8 | 9 | 8 | 9 | 11 | 28 | 35 | 8 | 7 | 6 |
| Level | Good | Good | Good | Good | Good | Good | Good | Moderate | Poor | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 6 | Good |
| Feb | 7 | Good |
| Mar | 8 | Good |
| Apr | 9 | Good |
| May | 8 | Good |
| Jun | 9 | Good |
| Jul | 11 | Good |
| Aug | 28 | Moderate |
| Sep | 35 | Poor |
| Oct | 8 | Good |
| Nov | 7 | Good |
| Dec | 6 | Good |
Where is Eureka?
Eureka sits at 40.8°N, 124.2°W, 39 ft above sea level, in United States. The nearest listed city is Bayside, 6.2 mi away.
Topography around Eureka
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Eureka.
Within 2 miles, the terrain around Eureka has only modest variations in elevation — a maximum elevation change of 302 ft around an average of 39 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,293 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 7,415 ft.
The land around Eureka is covered by water (35%) and artificial surfaces (32%) within 2 miles, water (46%) and trees (39%) within 10 miles, and trees (64%) and water (30%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Eureka (40.8021°, -124.1637°, elevation 39 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.