San Jacinto (CA) Temperature by Month

The average annual maximum temperature in San Jacinto, California, United States of America is 27°C (81°F), with daytime highs ranging from 18°C (64°F) in December to 37°C (99°F) in August. This page covers monthly averages, day-night differences, and how San Jacinto compares to cities worldwide.

The climate in San Jacinto is dynamic, ranging widely from pleasant in winter to very hot in summer. Nights are significantly colder, with lows dropping from 17°C (63°F) in August to 5°C (41°F) in December.

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

Low temperatures are most often recorded between 4 AM and 6 AM, while highs typically occur around 3 PM.

The chart below shows the average temperature throughout the year:

San Jacinto's average annual maximum temperature is 27°C (81°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.

Glasgow, Scotland averages 13°C (55°F) a year, mild but often grey, with cold winters and rarely hot summers.

Boston, USA averages 16°C (61°F) annually, with four distinct seasons and cold winters that rival northern Europe.

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.

Whether a city sits on the coast or deep inland makes a significant difference to its climate. Coastal areas tend to have more stable temperatures year-round, large bodies of water absorb heat slowly in summer and release it gradually in winter, keeping extremes in check. Cities far from the sea don't benefit from that buffer, which is why continental climates tend to have hotter summers and colder winters than their coastal counterparts at the same latitude.

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