Fountain Valley (CA) Temperature by Month

Fountain Valley, California, United States of America has an average annual maximum temperature of 23°C (73°F), with moderate seasonal shifts ranging from 19°C (66°F) in December to 27°C (81°F) in September. Below you'll find a full monthly breakdown and a comparison with cities worldwide.

Fountain Valley sees moderate fluctuations in temperatures, making each season distinct yet not extreme. Nights are considerably cooler, with lows ranging 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 Fountain Valley 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 290 hours of sunshine.

The chart below shows the average temperature throughout the year:

Fountain Valley'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:

Lisbon, Portugal averages 21°C (70°F) annually, warm summers, mild winters, and rain mainly in the cooler months.

Queenstown, New Zealand averages 10°C (50°F) annually, remember seasons are flipped, so its coldest months fall in June and July.

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

Adelaide, Australia averages 21°C (70°F) a year, with warm summers, mild winters, and relatively low rainfall year-round.

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 Fountain Valley's weather, including monthly rainfall, sunshine hours, and humidity, visit our Fountain Valley climate page.