San Diego Weather Averages
San Diego, California has an exceptionally moderate climate. Summers are cool and winters are warm. Storms are uncommon and rain is infrequent.
This page gives detailed information on annual temperature, precipitation, snow, sun, humidity, wind and storm averages for San Diego. The numbers here are historical averages based on climate data gathered at the San Diego International Airport, located on San Diego Bay near the city center.
Temperature
| 71 °F | annual average high | 22 °C |
| 59 °F | annual average low | 15 °C |
San Diego's coldest days of the year usually occur in the second half of December when the daily maximum temperature averages 66 degrees Fahrenheit (19 degrees Celsius) and the minimum averages 49 °F (9 °C).
The year's hottest days are normally in late August. The average temperature peaks then with daily highs of 78 °F (26 °C) and nighttime lows of 68 °F (20 °C).
| 192 days | 70 °F max. or more (21 °C) |
| 60 days | 50 °F min. or less (10 °C) |
Normally every day in San Diego has a temperature of 50 °F (10 °C) or more. The city averages three days a year when the thermometer reaches into the 90s °F (over 32 °C). The temperature doesn't normally climb above 100 °F (38 °C), even on the hottest days.
At night, the thermometer dips to 40 °F (4 °C) or below on average just once a year. San Diego usually never cold gets cold enough for frost.
Precipitation
| 9.8 in | total precipitation | 249 mm |
| 40 days | of rain or snowfall |
January and February are usually the wettest months of the year in San Diego, while summer months are the driest. San Diego's dry climate means that no month averages a total rainfall of more than 2.3 inches (58 mm).
Snow
| 0 in | total snowfall | 0 cm |
| 0 days | with new snow |
It normally never snows in San Diego. On rare occasions, the airport weather station has recorded a trace of snow.
Sun
| 68 % | sunshine |
| 146 days | clear skies |
The sun's rays reach the ground in San Diego during 68 percent of daylight hours on average year round, for a total of 3022 hours annually. Typically on 146 days a year the sky is mainly clear, with at most 30 percent cloud cover.
Sunlight in San Diego averages 12 hours and 10 minutes a day. The shortest days of the year in mid December have 10 hours and 0 minutes of daylight. The year's longest days in mid June last 14:19 from sunrise to sunset.
Humidity
| 69 % | average humidity |
The annual average for relative humidity in San Diego ranges throughout the day from 76 percent in the early morning to 58 percent at 1:00 pm.
| Local Time | 1 am | 4 am | 7 am | 10 am | 1 pm | 4 pm | 7 pm | 10 pm |
| Humidity % | 76 | 76 | 74 | 62 | 58 | 62 | 71 | 75 |
Wind
| 7.0 mph | wind speed average | 11.3 kph |
May is usually the windiest month for San Diego, and the wind is calmest during December.
Storms
| 6 days | precipitation of 0.5 inches (13 mm) or more |
| 3 days | with thunderstorms a year |
Heavy rainstorms are infrequent and snowstorms unheard of in San Diego. The city averages just two days a year when it rains an inch (25 mm) or more.
Thunderstorms, although not common in San Diego, can arrive at any time of the year.
Reference
The weather data here are long-term averages provided by the US National Centers for Environmental Information (NCEI). Temperature and precipitation are 1991-2020 normals while humidity and thunderstorms are 1961-1990 normals.