Eureka weather in August

In August, Eureka sees average daytime highs of 61°F and overnight lows near 54°F, with 0.2 in of rain across 0.9 wet days and about 13.6 hours of daylight. It is the 2nd-warmest and 11th-wettest month of the year here.

Day-to-day highs hold fairly steady near 61°F through the month. The sky is clear or mostly clear about 48% of the time in August, and the air most often feels dry.

Daylight stretches from about 14 h 12 min at the start of August to 13 hours by month's end. Set against the rest of the year, August is Eureka's 3rd-clearest and 10th-windiest month. For the whole year in context, see Eureka's year-round climate.

Daytime high
61°
2nd warmest
Overnight low
54°
12th coldest
Rainfall
0.2 in
0.9 wet days
Daylight
13 h 36 min
5:32 AM – 7:10 PM
Cloud cover
42%
3rd clearest
Wind
8 mph
10th windiest
Solar energy
6.73 kWh/m²
Travel score
6.3
out of 10

Eureka is city in and county seat of Humboldt County, California, United States.

Density
722/km²
people per km²
Founded
1850

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in August

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 61°F through the month.

A typical August day in Eureka reaches about 61°F in the afternoon and slips back to 54°F overnight — a 6°F spread between the day's warmth and the night's chill. On most days the high lands between 58°F and 64°F. Set against its neighbours, August runs on par with July and on par with September.

50°55°60°65°70°151015202531
Avg high (°F)Avg low (°F)
16054
26054
36054
46054
56054
66054
76054
86054
96054
106054
116054
126154
136154
146154
156154
166154
176154
186155
196155
206155
216155
226155
236155
246155
256155
266155
276155
286155
296155
306155
316155

Eureka weather by month

How August compares with the rest of the year at a glance. August is the 2nd-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan53° / 46°8.015.39.42.6
Feb53° / 46°6.713.410.42.6
Mar53° / 47°7.014.711.72.6
Apr53° / 48°4.111.813.13.0
May55° / 50°2.1714.23.9
Jun57° / 52°0.93.714.94.9
Jul60° / 53°0.10.814.66.0
Aug61° / 54°0.20.913.66.3
Sep61° / 54°0.62.312.36.3
Oct59° / 52°2.96.310.95.1
Nov55° / 49°5.712.59.73.3
Dec53° / 47°9.615.69.12.6

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 48% of the time in August.

Beyond those clear spells, partly cloudy skies cover about 21% of August, with mostly cloudy or overcast conditions the remaining 30%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16634
26634
36634
46535
56535
66535
76634
86733
96733
106832
116832
126832
136931
147030
157030
167030
177129
187129
197030
207030
217129
227129
237129
247228
257228
267327
277426
287426
297426
307624
317624

Chance of precipitation in August

Any precipitation

Eureka gets around 0.2 in of rain over 0.9 wet days in August. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 3% and peaks near 4% on the wettest days.

0%10%20%30%151015202531
Rain chance (%)
11
22
32
42
52
62
72
82
92
102
112
122
132
142
153
163
173
183
194
204
214
224
234
244
254
264
274
284
294
304
314

Humidity in August

DryComfortableHumidMuggyOppressiveMiserable

Most of August feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, August lands in the dry band about 70% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)
18317
28218
38119
48020
57822
67723
77525
87426
97228
107129
117030
126931
136832
146733
156634
166634
176535
186535
196535
206535
216535
226634
236634
246634
256733
266832
276832
286931
297030
307030
317129

Wind in August

Winds average 8 mph in August.

Across August, daily wind ranges from about 7 mph on the calmest days to 8 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
18light breeze
28light breeze
38light breeze
48light breeze
58light breeze
68light breeze
78light breeze
88light breeze
98light breeze
108light breeze
118light breeze
128light breeze
138light breeze
148light breeze
158light breeze
168light breeze
178light breeze
188light breeze
198light breeze
208light breeze
218light breeze
228light breeze
238light breeze
248light breeze
258light breeze
268light breeze
277light breeze
287light breeze
297light breeze
307light breeze
317calm

Sunrise & sunset in August

DaylightNight

Daylight runs from about 14 h 12 min at the start of August to 13 hours by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 72 minutes over August. Sunrise moves from 5:17 AM to 5:47 AM, and sunset from 7:29 PM to 6:47 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.25:177:29
214.25:187:28
314.15:197:27
414.15:207:25
514.15:217:24
614.05:227:23
714.05:237:22
814.05:247:21
913.95:257:19
1013.95:267:18
1113.85:277:17
1213.85:287:15
1313.85:297:14
1413.75:307:13
1513.75:317:11
1613.65:327:10
1713.65:337:09
1813.65:347:07
1913.55:357:06
2013.55:367:04
2113.45:377:03
2213.45:387:01
2313.35:396:59
2413.35:406:58
2513.35:416:56
2613.25:426:55
2713.25:436:53
2813.15:446:52
2913.15:456:50
3013.05:466:48
3113.05:476:47

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 6.73 kWh/m².

For context, solar energy here swings from a low near 1.64 kWh/m² to a high of 7.66 kWh/m² in July across the year — August's 6.73 kWh/m² sits near the top of that range.

02468151015202531
Solar energy (kWh/m²)Level
17.3Intense
27.2Intense
37.2Intense
47.2Intense
57.1Intense
67.1Intense
77.0Intense
87.0Intense
97.0Intense
107.0Intense
116.9Intense
126.9Intense
136.9Intense
146.8Intense
156.8Intense
166.8Intense
176.7Intense
186.7Intense
196.7Intense
206.6Intense
216.6Intense
226.5Intense
236.5Intense
246.5Intense
256.4Intense
266.4Intense
276.4Intense
286.3Intense
296.3Intense
306.2Intense
316.2Intense
Planning a trip in August

Hazard calendar for Eureka

In seasonPeak

None of Eureka's seasonal hazards are active in August. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

Eureka's rainy season runs November–March, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is August a good time to visit Eureka?

Our two travel scores rate August for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

6.3
Sightseeing
1st-best month of the year
Beach & pool
never really warm enough

August is a reasonable time to visit Eureka for sightseeing.

What to pack for Eureka in August

From August's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In August, Eureka sees daytime highs around 61°F and nights near 54°F. Pack sun protection. Worth having: a warm layer.

sun protectiona warm layer

Sea temperature near Eureka in August

The nearest coast averages about 55°F in August — 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.

50°52°54°56°JanFebMarAprMayJunJulAugSepOctNovDecbracing
Sea temperature (°F)Comfort
Jan52Bracing
Feb52Bracing
Mar51Bracing
Apr52Bracing
May52Bracing
Jun53Bracing
Jul54Bracing
Aug55Bracing
Sep55Bracing
Oct54Bracing
Nov53Bracing
Dec53Bracing

UV index in Eureka in August

LowModerateHighVery highExtreme

Clear-sky midday UV in August peaks around 8 (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.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateLowJun 21UV 9Dec 15UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May9Very high
Jun10Very high
Jul9Very high
Aug8Very high
Sep5High
Oct5Moderate
Nov2Low
Dec2Low

Air quality in Eureka in August

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where August 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).

010203040JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodSep 1234 µg/m³Dec 186 µg/m³
PM2.5 (µg/m³)Level
Jan6Good
Feb7Good
Mar8Good
Apr9Good
May8Good
Jun9Good
Jul11Good
Aug28Moderate
Sep35Poor
Oct8Good
Nov7Good
Dec6Good
Location & terrain

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.

2 miles
302 ft
10 miles
2,293 ft
50 miles
7,415 ft
treesgrasslandartificial surfacesbare terrainwaterwetland
August weather nearby: Bayside 6.2 mi · Arcata 6.2 mi · McKinleyville 11 mi · Redding 94 mi · Grants Pass 121 mi · Ashland 122 mi · Medford 125 mi · Ukiah 125 mi

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
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

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. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).