Average annual temperature is 10.2 °C
Absolute maximum temperature: 35.8 °C
Absolute minimum temperature: -21.6 °C
Number of sunny days: 234 days
Number of rainy days: 107 days
Number of snow days: 24 days
Look at detailed online map of South San Ysidro
* Weather data for South San Ysidro United States is based on climate observations for 2026 year
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Absolute maximum temperature (°C) | 9.6 | 11.9 | 15.3 | 23.5 | 25.7 | 32.4 | 35.8 | 34.0 | 30.5 | 25.0 | 20.4 | 10.5 |
| Average daytime temperature (°C) | 3.2 | 5.3 | 8.6 | 17.1 | 21.8 | 25.9 | 32.4 | 29.2 | 25.4 | 19.8 | 11.5 | 4.9 |
| Average temperature (°C) | -1.9 | -1.1 | 2.3 | 8.6 | 14.3 | 18.7 | 24.2 | 21.9 | 18.4 | 12.0 | 4.9 | -0.7 |
| Average night temperature (°C) | -5.8 | -6.2 | -2.9 | 1.1 | 7.2 | 10.7 | 15.0 | 14.5 | 11.2 | 4.9 | -0.1 | -5.0 |
| Absolute minimum temperature (°C) | -21.6 | -20.6 | -17.0 | -7.2 | 2.3 | 5.5 | 11.3 | 9.7 | 5.8 | -5.9 | -11.7 | -13.1 |
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight maximum duration (h) | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 14.0 | 14.0 | 13.0 | 12.0 | 11.0 | 10.0 | 9.0 |
| Daylight mean duration (h) | 10.1 | 10.9 | 12.0 | 13.1 | 14.0 | 14.5 | 14.3 | 13.5 | 12.4 | 11.3 | 10.3 | 9.8 |
| Daylight minimum duration (h) | 9.0 | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 13.0 | 12.0 | 11.0 | 10.0 | 9.0 | 9.0 |
| Sunshine mean duration (h) | 8.0 | 8.9 | 9.6 | 11.6 | 11.7 | 12.8 | 12.9 | 11.7 | 11.0 | 10.1 | 8.5 | 7.9 |
| Precipitation (mm) | 24 | 29 | 45 | 7 | 63 | 34 | 11 | 25 | 27 | 8 | 29 | 23 |
| Sunny days | 19 | 17 | 14 | 27 | 10 | 17 | 19 | 17 | 21 | 26 | 23 | 24 |
| Rainy days | 4 | 4 | 12 | 3 | 21 | 13 | 12 | 14 | 9 | 5 | 5 | 5 |
| Snow days | 8 | 7 | 5 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 2 |
The largest precipitation sum in South San Ysidro is at