Walnut in Summer
In summer (June, July and August), Walnut sees average daytime highs around 84°F and overnight lows near 63°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 87°F by late August. The sky is clear or mostly clear about 86% of the time across summer, and the air most often feels comfortable.
Summer is Walnut's 3rd-best season to visit on our travel score. For the whole year in context, see Walnut's year-round climate.
- Avg daytime high
- 84°F
- warmest season of the year
- Avg overnight low
- 63°F
- Rainfall
- 0.2 in
- 1 wet days
- Avg wind
- 3 mph
- Travel score
- 7.5
- 3rd-best season
- Months
- Jun · Jul · Aug
Temperature in Walnut in Summer
Over the season highs climb from about 76°F in early June to 87°F by late August.
A typical summer day in Walnut reaches about 84°F and drops to 63°F overnight. The warmest of the three months is August, the coolest June.
Walnut 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 | 63° / 44° | 3.6 | 5.9 | 10 | 6.2 |
| Feb | 63° / 46° | 4.0 | 6.6 | 10.7 | 6.2 |
| Mar | 66° / 48° | 2.4 | 6.3 | 11.7 | 6.8 |
| Apr | 70° / 51° | 1.0 | 3.7 | 12.8 | 7.8 |
| May | 74° / 55° | 0.4 | 2.2 | 13.7 | 8.6 |
| Jun | 79° / 59° | 0.1 | 0.3 | 14.2 | 8.9 |
| Jul | 85° / 64° | 0.1 | 0.5 | 14 | 7.1 |
| Aug | 87° / 65° | 0.0 | 0.2 | 13.3 | 6.5 |
| Sep | 84° / 63° | 0.2 | 0.9 | 12.2 | 7.4 |
| Oct | 78° / 57° | 0.7 | 2.6 | 11.1 | 8.7 |
| Nov | 69° / 49° | 1.0 | 2.8 | 10.2 | 8.0 |
| Dec | 62° / 44° | 2.5 | 5.3 | 9.8 | 6.3 |
Cloud cover in Summer
The sky is clear or mostly clear about 86% of the time across summer.
Chance of precipitation in Summer
Walnut 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 comfortable — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 3 mph across summer.
Sunrise & sunset in Summer
Daylight runs from about 14 h 06 min in early June to 12 h 48 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 7.8 kWh/m².
Is summer a good time to visit Walnut?
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 Walnut for general sightseeing. The water and warmth also suit a beach or pool day.
What to pack for Walnut in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, Walnut sees daytime highs around 84°F and nights near 63°F. Pack light clothes and sun protection.
Sea temperature near Walnut in Summer
The nearest coast averages about 68°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 27 mi away) is warmest in August at about 69°F and coldest in February near 59°F.
It's comfortable for a long swim from Jul 13 to Sep 28 — about 2.6 months when the water holds above 68°F.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°F) | 59 | 59 | 59 | 60 | 63 | 65 | 68 | 69 | 69 | 67 | 64 | 60 |
| Comfort | Cool | Cool | Cool | Cool | Cool | Cool | Refreshing | Refreshing | Refreshing | Cool | Cool | Cool |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 59 | Cool |
| Feb | 59 | Cool |
| Mar | 59 | Cool |
| Apr | 60 | Cool |
| May | 63 | Cool |
| Jun | 65 | Cool |
| Jul | 68 | Refreshing |
| Aug | 69 | Refreshing |
| Sep | 69 | Refreshing |
| Oct | 67 | Cool |
| Nov | 64 | Cool |
| Dec | 60 | Cool |
UV index in Walnut 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 Walnut peaks around July 11 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 16 at about 3 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 4 | 5 | 5 | 8 | 8 | 11 | 11 | 10 | 8 | 6 | 3 | 3 |
| Level | Moderate | Moderate | Moderate | Very high | Very high | Extreme | Extreme | Extreme | Very high | High | Moderate | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 4 | Moderate |
| Feb | 5 | Moderate |
| Mar | 5 | Moderate |
| Apr | 8 | Very high |
| May | 8 | Very high |
| Jun | 11 | Extreme |
| Jul | 11 | Extreme |
| Aug | 10 | Extreme |
| Sep | 8 | Very high |
| Oct | 6 | High |
| Nov | 3 | Moderate |
| Dec | 3 | Moderate |
Air quality in Walnut 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 Walnut is worst in September — around 49 µg/m³ PM2.5 (poor), about 4.0× the cleanest month (May, 12 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) | 18 | 19 | 19 | 17 | 12 | 17 | 19 | 32 | 49 | 21 | 21 | 18 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Poor | Moderate | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 18 | Moderate |
| Feb | 19 | Moderate |
| Mar | 19 | Moderate |
| Apr | 17 | Moderate |
| May | 12 | Moderate |
| Jun | 17 | Moderate |
| Jul | 19 | Moderate |
| Aug | 32 | Moderate |
| Sep | 49 | Poor |
| Oct | 21 | Moderate |
| Nov | 21 | Moderate |
| Dec | 18 | Moderate |
Where is Walnut?
Walnut sits at 34.0°N, 117.9°W, 561 ft above sea level, in United States. The nearest listed city is South San Jose Hills, 2.5 mi away.
Topography around Walnut
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Walnut.
Within 2 miles, the terrain around Walnut has only modest variations in elevation — a maximum elevation change of 797 ft around an average of 663 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,756 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 10,013 ft.
The land around Walnut is covered by artificial surfaces (71%) within 2 miles, artificial surfaces (60%) within 10 miles, and artificial surfaces (27%) 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 Walnut (34.0203°, -117.8653°, elevation 561 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.