San Ysidro (CA) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit San Ysidro.
Climate overview of San Ysidro
San Ysidro, California, United States of America, experiences moderate temperature changes through the seasons. September is the warmest month with daytime highs of 27°C (81°F), while December is the coolest at 19°C (66°F).
With just 220 mm (8.7 in) of annual rainfall, the city has a dry, desert-like climate. The sunniest month is July, with 10.4 hours of sunshine per day on average.
San Ysidro Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in San Ysidro - and find the best time to visit.
Monthly Temperature in San Ysidro
The climate in San Ysidro experiences moderate temperature changes, with mild shifts between seasons. Average daytime temperatures reach a comfortable 27°C (81°F) in September. In December, the coolest month of the year, temperatures drop to a pleasant 19°C (66°F).
At night, temperatures range from around 18°C (64°F) in September to 8°C (46°F) in December.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in San Ysidro
San Ysidro has a dry climate with very low precipitation, averaging 220 mm (8.7 in) of rainfall annually. San Ysidro can be quite wet during December, receiving approximately 58 mm (2.3 in) of precipitation over 8 rainy days.
In contrast, during the driest month (June), you will experience much drier conditions, with 0.3 mm (0.01 in) of precipitation spread across 0 rainy days. For more details, please visit our San Ysidro Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Sunshine Hours in San Ysidro
San Ysidro experiences moderate variation in sunshine hours across the seasons. With 10.4 hours daily sunshine in July, it dips to 7.3 hours in January, offering a balanced mix of sunny and overcast days.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Daily percentage of sunshine
Humidity in San Ysidro by Month
The relative humidity is high throughout the year in San Ysidro.
The city experiences its highest humidity in July, reaching 80%. In November, the humidity drops to its lowest level at 69%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Best Time to Visit San Ysidro
Monthly ratings reflect general weather comfort, based on daytime temperature and rainfall. Swimming and winter conditions are highlighted separately where relevant.
- Best overall: January, February, March, April, May, June, July, August, September, October and November
- Warmest weather: July, August, September and October
- Most sunshine: July
- Fewer rainy days: May, June, July, August and September
- Seasonal pattern: Very little rainfall for most of the year
Frequently asked questions about the climate in San Ysidro
What is the best time to visit San Ysidro?
January, February, March, April, May, June, July, August, September, October and November typically offer the most optimal weather in San Ysidro. In contrast, December tends to have less optimal conditions. San Ysidro has very little rainfall for most of the year.
What temperatures can I expect in San Ysidro?
Daytime highs range from 19°C (66°F) in December to 27°C (81°F) in September. Nighttime lows range from 8°C (46°F) to 18°C (64°F).
How much rain does San Ysidro get?
Annual rainfall is around 220 mm (8.7 in). December is the wettest month with 58 mm (2.3 in), while June is the driest with 0.3 mm (0.01 in).
How sunny is San Ysidro?
San Ysidro receives around 3,037 hours of sunshine per year. July is the sunniest month with 312 hours, while January is the cloudiest with just 219 hours. Overall, San Ysidro enjoys abundant sunshine.
San Ysidro 3-Day Forecast
San Ysidro on the map
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