Historical weather data, all-time temperature records, and monthly climate averages for San Ramon, CA. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
July 23rd is etched into San Ramon's weather history — it's the same date the city hit its all-time record high of 114° back in 2006. That scorcher is the most extreme temperature ever recorded here across three decades of data.
San Ramon's thermometer has swung from a brutal 114° in July 2006 down to a bitter 25° in January 1997 — a 89-degree spread that captures just how variable inland Bay Area weather can get. Summers bring relentless heat while winter nights can dip well below freezing.
San Ramon peaks in late July and August with average highs around 82-83°, making it a classic warm inland valley summer. Winters are mild by day but cool quickly, with December highs averaging just 53°. Rain is concentrated in the winter months, with early January typically the wettest stretch of the year.