Vallejo in Summer
In summer (June, July and August), Vallejo sees average daytime highs around 80°F and overnight lows near 56°F, with 0.2 in of rain over about 1 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 76°F in early June to 82°F by late August. The sky is clear or mostly clear about 87% of the time across summer, and the air most often feels dry.
Summer is Vallejo's best season of the year to visit on our travel score. For the whole year in context, see Vallejo's year-round climate.
- Avg daytime high
- 80°F
- warmest season of the year
- Avg overnight low
- 56°F
- Rainfall
- 0.2 in
- 1 wet days
- Avg wind
- 7 mph
- Travel score
- 8.9
- best season of the year
- Months
- Jun · Jul · Aug
Temperature in Vallejo in Summer
Over the season highs climb from about 76°F in early June to 82°F by late August.
A typical summer day in Vallejo reaches about 80°F and drops to 56°F overnight. The warmest of the three months is August, the coolest June.
Vallejo 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 | 57° / 42° | 4.0 | 9.3 | 9.7 | 4.2 |
| Feb | 61° / 44° | 4.2 | 8.8 | 10.5 | 5.0 |
| Mar | 64° / 46° | 3.1 | 8.7 | 11.7 | 6.1 |
| Apr | 68° / 48° | 1.4 | 4.9 | 13 | 7.3 |
| May | 74° / 52° | 0.7 | 3 | 14 | 8.4 |
| Jun | 79° / 55° | 0.2 | 0.8 | 14.6 | 8.9 |
| Jul | 80° / 56° | 0.0 | 0.1 | 14.4 | 9.0 |
| Aug | 81° / 56° | 0.0 | 0.2 | 13.5 | 8.9 |
| Sep | 81° / 55° | 0.1 | 0.4 | 12.3 | 8.8 |
| Oct | 75° / 52° | 0.9 | 3 | 11 | 8.5 |
| Nov | 65° / 46° | 1.9 | 5.6 | 9.9 | 6.5 |
| Dec | 57° / 42° | 3.7 | 9.3 | 9.4 | 4.3 |
Cloud cover in Summer
The sky is clear or mostly clear about 87% of the time across summer.
Chance of precipitation in Summer
Vallejo gets around 0.2 in of rain over 1 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 7 mph across summer.
Sunrise & sunset in Summer
Daylight runs from about 14 h 24 min in early June to 12 h 54 min 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 7.7 kWh/m².
Hazard calendar for Vallejo
None of Vallejo's seasonal hazards peak in summer. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do.
Vallejo's rainy season runs November–March, when most of the year's rain falls.
Is summer a good time to visit Vallejo?
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 one of the better times to visit Vallejo for general sightseeing. The water and warmth also suit a beach or pool day.
What to pack for Vallejo in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, Vallejo sees daytime highs around 80°F and nights near 56°F. Pack light clothes and sun protection.
Sea temperature near Vallejo in Summer
The nearest coast averages about 56°F across summer — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 25 mi away) is warmest in September at about 58°F and coldest in April near 53°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) | 53 | 53 | 54 | 53 | 53 | 54 | 56 | 58 | 58 | 57 | 55 | 54 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 53 | Bracing |
| Feb | 53 | Bracing |
| Mar | 54 | Bracing |
| Apr | 53 | Bracing |
| May | 53 | Bracing |
| Jun | 54 | Bracing |
| Jul | 56 | Bracing |
| Aug | 58 | Bracing |
| Sep | 58 | Bracing |
| Oct | 57 | Bracing |
| Nov | 55 | Bracing |
| Dec | 54 | Bracing |
UV index in Vallejo in Summer
Clear-sky midday UV across summer averages around 10 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Vallejo peaks around July 11 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 at about 2 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 2 | 4 | 5 | 6 | 8 | 10 | 10 | 10 | 6 | 5 | 2 | 2 |
| Level | Moderate | Moderate | Moderate | High | Very high | Extreme | Extreme | Very high | High | High | Moderate | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 2 | Moderate |
| Feb | 4 | Moderate |
| Mar | 5 | Moderate |
| Apr | 6 | High |
| May | 8 | Very high |
| Jun | 10 | Extreme |
| Jul | 10 | Extreme |
| Aug | 10 | Very high |
| Sep | 6 | High |
| Oct | 5 | High |
| Nov | 2 | Moderate |
| Dec | 2 | Low |
Air quality in Vallejo 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 Vallejo is worst in September — around 29 µg/m³ PM2.5 (moderate), about 4.2× the cleanest month (June, 7 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) | 13 | 13 | 13 | 10 | 8 | 7 | 10 | 25 | 29 | 27 | 16 | 12 |
| Level | Moderate | Moderate | Moderate | Good | Good | Good | Good | Moderate | Moderate | Moderate | Moderate | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 13 | Moderate |
| Feb | 13 | Moderate |
| Mar | 13 | Moderate |
| Apr | 10 | Good |
| May | 8 | Good |
| Jun | 7 | Good |
| Jul | 10 | Good |
| Aug | 25 | Moderate |
| Sep | 29 | Moderate |
| Oct | 27 | Moderate |
| Nov | 16 | Moderate |
| Dec | 12 | Good |
Where is Vallejo?
Vallejo sits at 38.1°N, 122.3°W, 69 ft above sea level, in United States. The nearest listed city is American Canyon, 5.0 mi away.
Topography around Vallejo
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Vallejo.
Within 2 miles, the terrain around Vallejo has only modest variations in elevation — a maximum elevation change of 312 ft around an average of 39 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,473 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,459 ft.
The land around Vallejo is covered by artificial surfaces (51%) within 2 miles, water (34%) and grassland (33%) within 10 miles, and grassland (29%), trees (24%) and water (24%) 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 Vallejo (38.1041°, -122.2566°, elevation 69 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.