Irvine (CA) Temperature by Month

Irvine in California, United States of America sees moderate seasonal temperature shifts, with daytime highs between 20°C (68°F) in December and 29°C (84°F) in September, averaging 24°C (75°F) annually. Explore the full monthly breakdown below.

The climate in Irvine experiences moderate temperature changes, with mild shifts between seasons. At night, temperatures range from 18°C (64°F) in September to 8°C (46°F) in December.

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

The coldest point of the day usually falls between 4 AM and 6 AM, with temperatures peaking around 3 PM. September, the city's warmest month, gets 290 hours of sunshine.

The chart below shows the average temperature throughout the year:

Irvine's average annual maximum temperature is 24°C (75°F). To put that in context, here's how it compares to a few well-known destinations:

Rome, Italy averages 20°C (68°F) annually, with reliably warm summers and comfortable winters.

Toronto, Canada averages 13°C (55°F) annually, with cold snowy winters balanced by genuinely warm summers.

New York City, USA averages 17°C (63°F) a year, with hot humid summers and cold winters that bring regular snowfall.

Melbourne, Australia averages 20°C (68°F) annually, known for unpredictable weather, with four seasons sometimes happening in one day.

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.

Global average temperatures have risen by around 1.2°C since the pre-industrial era, and the effects are visible across many regions. Winters are milder on average, with fewer frost days and less snow in many parts of the world. Heatwaves are more frequent and more intense, and Europe's summers of 2018, 2019, and 2020 all set records.

Summers are also getting drier in some areas, while winter rainfall has increased in others. This contributies to higher river levels and more flooding. In many countries, spring arrives earlier and autumn lasts longer. It has knock-on effects for wildlife, agriculture, and local ecosystems.

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