San Dimas in Winter
In winter (December, January and February), San Dimas sees average daytime highs around 63°F and overnight lows near 45°F, with 10.1 in of rain over about 18 wet days across the season. It is the coldest season of the year and the wettest season of the year.
Across winter, daytime highs hold fairly steady around 63°F. The sky is clear or mostly clear about 48% of the time across winter, and the air most often feels dry.
Winter is San Dimas's weakest season of the year to visit on our travel score. For the whole year in context, see San Dimas's year-round climate.
- Avg daytime high
- 63°F
- coldest season of the year
- Avg overnight low
- 45°F
- Rainfall
- 10.1 in
- 18 wet days
- Avg wind
- 3 mph
- Travel score
- 6.2
- weakest season of the year
- Months
- Dec · Jan · Feb
Temperature in San Dimas in Winter
Across winter, daytime highs hold fairly steady around 63°F.
A typical winter day in San Dimas reaches about 63°F and drops to 45°F overnight. The warmest of the three months is February, the coolest December.
San Dimas weather by month
How the three winter months (December, January and February) 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 | 13.8 | 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 Winter
The sky is clear or mostly clear about 48% of the time across winter.
Chance of precipitation in Winter
San Dimas gets around 10.1 in of rain over 18 wet days across winter. The line is the day-by-day chance of measurable precipitation.
Humidity in Winter
Most of winter feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Winter
Winds average 3 mph across winter.
Sunrise & sunset in Winter
Daylight runs from about 9 h 54 min in early December to 11 h 12 min by late February. The lit band spans sunrise to sunset each day.
Solar energy in Winter
Average shortwave solar energy reaching the ground each day across winter, about 3.3 kWh/m².
Is winter a good time to visit San Dimas?
Our two travel scores rate winter for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
winter is a reasonable time to visit San Dimas for sightseeing.
What to pack for San Dimas in Winter
From winter's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In winter, San Dimas sees daytime highs around 63°F and nights near 45°F. Worth packing: a warm layer. About 18 days see rain.
Sea temperature near San Dimas in Winter
The nearest coast averages about 60°F across winter — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 34 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 San Dimas in Winter
Clear-sky midday UV across winter averages around 4 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in San Dimas 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 San Dimas in Winter
Average fine-particle pollution (PM2.5) through the year — so you can see where winter falls, not just the annual average.
Air quality in San Dimas 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 San Dimas?
San Dimas sits at 34.1°N, 117.8°W, 955 ft above sea level, in United States. The nearest listed city is La Verne, 2.5 mi away.
Topography around San Dimas
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of San Dimas.
Within 2 miles, the terrain around San Dimas has significant variations in elevation — a maximum elevation change of 942 ft around an average of 991 ft above sea level; within 10 miles, very significant variations in elevation — a maximum elevation change of 5,371 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 10,013 ft.
The land around San Dimas is covered by artificial surfaces (60%) within 2 miles, artificial surfaces (48%), trees (23%) and shrubs (20%) within 10 miles, and artificial surfaces (27%), shrubs (20%) and grassland (20%) 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 San Dimas (34.1067°, -117.8067°, elevation 955 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.