South San Francisco receives its highest rainfall in Dec, while humidity peaks during summer months.
🌧️ Wettest:Dec — 102 mm☀️ Driest:Jul — 2 mm
💧 Humidity peaks at 86% in Jul · annual avg 83%
🌍 Climate Summary
Avg Annual Temp:58.6°F
Avg Annual Rainfall:532 mm
Avg Humidity:83%
Data Period:1981 – 2025
South San Francisco Climate Overview
South San Francisco has a warm temperate climate with warm summers and mild winters.
Temperatures peak in Sep and drop to their lowest in Dec,
while rainfall is highest during winter months.
Humidity remains high throughout the year creating warm and humid conditions.
📈 Yearly Trends
The warmest year in South San Francisco's recorded history was 2014
(avg: 61.5°F),
while the coldest year was 1982
(avg: 55.9°F),
based on annual average temperatures.
📊 Key Climate Trends
🌡️ South San Francisco's temperature has remained relatively stable over the past decade
📈 Minimum temperatures show a slight warming trend in recent years
🌧️ Rainfall varies year-to-year without a clear long-term trend
🌡️ Annual Temperature Trend
View Range:
Average annual high/low · Last 10 years · °F
South San Francisco's temperatures has remained relatively stable over the past decade.
The highest recorded temperature reached
93.9°F in Sep 2017,
while the lowest dropped to
31.3°F in Feb 1989.
🌧️ Annual Precipitation
View Range:
Total annual precipitation · Last 10 years · mm/year
Annual rainfall in South San Francisco shows noticeable variation. Rainfall varies year-to-year without a clear long-term trend.
What is the hottest month in South San Francisco?▼
Based on 45 years of data (1981–2025), Sep is typically the hottest month in South San Francisco, California, with average high temperatures around 79.3°F.
What is the coldest month in South San Francisco?▼
Dec is the coldest month in South San Francisco, with average low temperatures around 40.8°F.
What is the rainiest month in South San Francisco?▼
Dec receives the most rainfall with approximately 102 mm, while Jul is the driest with 2 mm.
What was the highest temperature ever recorded in South San Francisco?▼
The highest recorded temperature was 93.9°F in Sep 2017. This is part of the historical record spanning 1981–2025.
What was the lowest temperature ever recorded in South San Francisco?▼
The lowest recorded temperature was 31.3°F in Feb 1989.
How many years of data does this page cover?▼
This page covers 45 years of climate data from 1981 to 2025. As new data is added to the database the page automatically reflects the updated coverage.
How much sunlight does South San Francisco get?▼
South San Francisco receives the most sunlight in Jun with an average solar radiation of 7.12 kWh/m²/day. This solar radiation data, sourced from NASA POWER, is useful for solar energy planning, agriculture, and understanding seasonal sunshine availability in California.
Where does this weather data come from?▼
All climate data is sourced from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite and model data. It provides monthly averages for temperature, precipitation, humidity, wind speed, and solar radiation.
📚 Data Source
All weather data is sourced from NASA POWER (Prediction of Worldwide Energy Resources), a NASA project providing solar and meteorological data for renewable energy, building efficiency, and agricultural research.