San Luis Obispo (CA) Temperature by Month

San Luis Obispo, California, United States of America has an average annual maximum temperature of 23°C (73°F), with moderate seasonal shifts ranging from 17°C (63°F) in December to 28°C (82°F) in September. Below you'll find a full monthly breakdown and a comparison with cities worldwide.

San Luis Obispo sees moderate fluctuations in temperatures, making each season distinct yet not extreme. Nights are considerably cooler, with lows ranging from 12°C (54°F) in September to 5°C (41°F) in December.

The chart below illustrates the average maximum day and minimum night temperatures in San Luis Obispo by month:

Daily lows are most common between 4 AM and 6 AM. By 3 PM temperatures reach their daily high, driven by peak solar heating. September, the warmest month of the year, receives 270 hours of sunshine.

The chart below shows the average temperature throughout the year:

San Luis Obispo's average annual maximum temperature is 23°C (73°F). To put that in context, here's how it compares to a few well-known destinations:

Seville, Spain averages 23°C (73°F) a year, one of the warmer cities in Western Europe, with long hot summers.

Interlaken, Switzerland averages 8°C (46°F) a year, with cold winters and cool summers thanks to its Alpine setting.

Seoul, South Korea averages 18°C (64°F) a year, with four clear seasons, cold winters, and hot humid summers.

Tokyo, Japan averages 21°C (70°F) a year, with hot summers, cool winters, and a well-defined cherry blossom spring.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

Seasonal temperature shifts influence more than just how warm it feels, they also drive changes in rainfall, cloud cover, and wind patterns throughout the year.

Warmer air holds more moisture, which tends to mean heavier or more frequent rain during the warmer months. When temperatures drop in winter, any precipitation that does fall is more likely to come as snow or sleet, though in San Luis Obispo this rarely lasts long on the ground.

For more on San Luis Obispo's weather, including monthly rainfall, sunshine hours, and humidity, visit our San Luis Obispo climate page.