Hercules, United States experiences average highs of 22°C (72°F) and lows of 10°C (50°F) throughout the year. The climate is relatively dry, with only 4 rainy days per month on average. Sunshine is abundant, averaging about 10 hours per day. Average highs have stayed broadly stable across the available records.
Hercules, United States Weather & Climate 2026
Monthly climate averages for Hercules, 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
8.1/10
Best: May, June, July, August, September
UV Index
6
High
Temperature 22°C / 10°C
Feels Like 21°C / 8°C
Rainy Days 4
Rainfall 43 mm
Sunshine 10 h
Humidity 71%
Wind Speed 16 km/h
Dew Point 11°C
Frost Days 1 days
Hottest Month
28°C
August
Avg Low14°C
Rain0days
Coldest Month
6°C
January
Avg High15°C
Rain10days
Driest Month
0days
June
Avg High27°C
Avg Low13°C
Windiest Month
19 km/h
June (Gusts 44)
Sea Temperature
11°C – 22°C
Warmest water: August (
22°C
)
Worst Time to Visit
Consider avoiding January, February, December due to less favorable weather conditions.
Sun Position
Sunrise 05:47
Daylight 14.8h
Sunset 20:35
Live conditions—
Hercules on the map · live conditions
Hercules, United States
- Continent
- Americas
- Country
- United States
- City
- Hercules
- Population
- 25.3K
- Elevation
- 24 m
- Coordinates
- 38.02°, -122.29°
Seasonal Breakdown
Spring
Mar–May
Avg High 21°C
Avg Low 9°C
Rain 6 days/mo
1/3 best months
Summer
Jun–Aug
Avg High 28°C
Avg Low 13°C
Rain 0 days/mo
3/3 best months
Autumn
Sep–Nov
Avg High 24°C
Avg Low 12°C
Rain 3 days/mo
1/3 best months
Winter
Dec–Feb
Avg High 15°C
Avg Low 6°C
Rain 9 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: 15°C / 6°C . Feb: 17°C / 6°C . Mar: 18°C / 7°C . Apr: 21°C / 9°C . May: 24°C / 11°C . Jun: 27°C / 13°C . Jul: 27°C / 13°C . Aug: 28°C / 14°C . Sep: 28°C / 14°C . Oct: 25°C / 12°C . Nov: 19°C / 8°C . Dec: 15°C / 6°C .
Monthly Rainfall
Rainfall
Bar chart showing monthly rainfall. Jan: 112 mm. Feb: 94 mm. Mar: 94 mm. Apr: 26 mm. May: 16 mm. Jun: 1 mm. Jul: 0 mm. Aug: 0 mm. Sep: 4 mm. Oct: 26 mm. Nov: 51 mm. Dec: 96 mm.
Monthly Humidity
Humidity
Line chart showing monthly humidity. Jan: 82%. Feb: 75%. Mar: 75%. Apr: 70%. May: 66%. Jun: 63%. Jul: 67%. Aug: 68%. Sep: 67%. Oct: 63%. Nov: 73%. Dec: 81%.
Monthly Wind Speed
Wind SpeedGusts
Bar chart showing monthly wind speed. Jan: 14 km/h . Feb: 16 km/h . Mar: 17 km/h . Apr: 18 km/h . May: 19 km/h . Jun: 19 km/h . Jul: 18 km/h . Aug: 17 km/h . Sep: 16 km/h . Oct: 14 km/h . Nov: 12 km/h . Dec: 13 km/h .
Sunshine
Sunshine
Sunshine: Jan: 7h. Feb: 8h. Mar: 9h. Apr: 11h. May: 13h. Jun: 13h. Jul: 13h. Aug: 12h. Sep: 11h. Oct: 10h. Nov: 8h. Dec: 6h.
Sea Temperature
Sea Temperatureswim
Line chart showing monthly sea temperature. Jan: 11°C . Feb: 12°C . Mar: 13°C . Apr: 16°C . May: 19°C . Jun: 21°C . Jul: 22°C . Aug: 22°C . Sep: 22°C . Oct: 20°C . Nov: 15°C . Dec: 12°C .
UV Index
UV Index
Bar chart showing monthly UV index. Jan: UV 3. Feb: UV 4. Mar: UV 5. Apr: UV 7. May: UV 8. Jun: UV 8. Jul: UV 8. Aug: UV 8. Sep: UV 6. Oct: UV 5. Nov: UV 3. Dec: UV 3.
Monthly Daylight Hours
Daylight12h reference
Monthly Dew Point & Comfort
Dew Point Dry Comfortable Humid Muggy Oppressive
Climate Trends
Average highs have stayed broadly stable across the available records. Average rainfall is trending drier by about 15 mm.
2016 to 2025
Avg high Avg rainfall
Climate summary
| Last 12 months | All years | |
|---|---|---|
| Hottest month | Aug 2025 · 29°C | Aug · 28°C |
| Coldest month | Jan 2025 · 5°C | Jan · 6°C |
| Wettest month | Feb 2025 · 137 mm | Jan · 112 mm |
| Windiest month | Mar 2025 · 20 km/h | Jun · 19 km/h |
Month-by-Month Weather Table
January
Fair 
February
Fair March
Good April
Good May best
Excellent June best
Excellent July best
Excellent August best
Excellent September best
Excellent October
Excellent November
Good December
Fair | Month | Temp | Feels Like | Rain | Sun | Humidity | UV | Status | Details |
|---|---|---|---|---|---|---|---|---|
| January | 15°C / 6°C | 13°C / 4°C | 10days (112 mm) Wet | 6.6h Fair | 82% Humid | 2.9 Moderate | Fair | View Details |
| February | 17°C / 6°C | 15°C / 4°C | 7days (94 mm) Good | 8.3h Good | 75% Muggy | 3.7 Moderate | Fair | View Details |
| March | 18°C / 7°C | 16°C / 5°C | 11days (94 mm) Wet | 9.2h Good | 75% Muggy | 5.4 High | Good | View Details |
| April | 21°C / 9°C | 20°C / 7°C | 4days (26 mm) Good | 11h Excellent | 70% Muggy | 6.9 High | Good | View Details |
| May best | 24°C / 11°C | 23°C / 9°C | 2days (16 mm) Excellent | 12.5h Excellent | 66% Muggy | 7.9 Very High | Excellent | View Details |
| June best | 27°C / 13°C | 27°C / 11°C | 0days (1 mm) Excellent | 13.4h Excellent | 63% Muggy | 8.2 Very High | Excellent | View Details |
| July best | 27°C / 13°C | 28°C / 12°C | 0days (0 mm) Excellent | 13.2h Excellent | 67% Muggy | 8.3 Very High | Excellent | View Details |
| August best | 28°C / 14°C | 29°C / 14°C | 0days (0 mm) Excellent | 12.4h Excellent | 68% Muggy | 7.7 Very High | Excellent | View Details |
| September best | 28°C / 14°C | 28°C / 14°C | 1days (4 mm) Excellent | 11.2h Excellent | 67% Muggy | 6.4 High | Excellent | View Details |
| October | 25°C / 12°C | 24°C / 11°C | 2days (26 mm) Excellent | 9.5h Good | 63% Muggy | 5 Moderate | Excellent | View Details |
| November | 19°C / 8°C | 17°C / 7°C | 6days (51 mm) Good | 7.9h Good | 73% Muggy | 3.4 Moderate | Good | View Details |
| December | 15°C / 6°C | 13°C / 4°C | 9days (96 mm) Wet | 6.3h Fair | 81% Humid | 2.6 Moderate | Fair | View Details |
Compare Nearby City Climates
Frequently Asked Questions
The best months to visit Hercules are May, June, July, August, September, when temperatures are comfortable and rainfall is at its lowest. This is based on 10-year climate averages for Hercules, scoring temperature, rainfall, humidity, and sunshine hours.
The hottest month in Hercules is August, with average daytime highs of 28°C (83°F). Plan outdoor activities for early morning or late afternoon if visiting during this period.
The coldest month in Hercules is January, with average overnight lows of 6°C (43°F). Pack warm layers and expect shorter daylight hours during this period.
The wettest month in Hercules is January, averaging 112mm of precipitation across 10 rainy days. An umbrella or waterproof jacket is essential.
The rainy season in Hercules runs through March, January, with the heaviest rainfall in March. Based on 10-year averages for Hercules.
Hercules receives approximately 122 sunshine hours per year. The sunniest month is June with around 13 hours. Based on climate data for Hercules.
The least favorable months to visit Hercules are January, February, December, primarily due to less favorable weather conditions. For the best conditions, consider May, June, July, August, September instead.
The annual average UV index in Hercules is 6, classified as high. Standard sun protection (sunscreen, hat) is recommended during prolonged outdoor exposure.
Average humidity in Hercules is 71%, classified as moderate. Humidity levels are generally comfortable and should not affect outdoor activities for most people.
Yes — sea temperatures in August average 22°C (72°F), which is warm and comfortable for swimming and water activities.
Hercules rarely sees significant snowfall but does experience frost, averaging 1 frost days during the colder months.
Average wind speeds in Hercules are 16 km/h (10 mph). The windiest month is June with peak winds reaching 19 km/h (12 mph) (gusts up to 44 km/h / 27 mph).
Hercules averages 8 clear-sky days per month with overall cloud cover around 43%. The clearest skies occur in October.
The annual average dew point in Hercules is 11°C (52°F), which feels pleasant with low humidity. Outdoor activities are comfortable year-round from a humidity standpoint.
Hercules 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 Hercules ranges from 8°C (46°F) to 21°C (70°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 Hercules. It earns a climate score of 9.5/10 with Excellent.
For June in Hercules, pack Breathable clothing, Sunscreen (SPF 30+), Sun hat, Sunglasses, Comfortable walking shoes. With average highs of 27°C (81°F) and 0 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.
Last updated: