San Diego, California weather in January

Averages from 2021–2025 (155 days of record).

Average high

63°F

Average low

47°F

Rainy days

~7 per month

Total precipitation

2.8 in

Warmest recorded

86°F

Coldest recorded

37°F

Expect January days in San Diego, California to top out around 63°F and cool to about 47°F overnight, with roughly 7 days of measurable rain across the month. In recent years January has ranged from 37°F to 86°F.