Weather and climate in Fountain Valley, CA
What the weather is like in Fountain Valley
The warmest month in Fountain Valley is September, with average highs of 73°F. The coolest is February, when nights average 54°F. About 12.2 in of rain and snow falls in a typical year, most in February and least in June.
Skies are clearest in October (48% average cloud cover) and cloudiest in June (68%). Combining cloud with the length of truly dark nights, November, December, January offer the most clear, dark hours for stargazing.
Clear, dark hours per night
Hours of full astronomical darkness in mid-month, multiplied by the average share of clear sky. A rough guide to how much good observing time a typical night offers.
Monthly averages
| Month | High | Low | Precipitation | Cloud cover | Humidity | Wind | Dark hours |
|---|---|---|---|---|---|---|---|
| January | 63°F | 54°F | 2.7 in | 52% | 68% | 6 mph | 10.9 h |
| February | 62°F | 54°F | 2.8 in | 54% | 72% | 6 mph | 10.2 h |
| March | 62°F | 55°F | 1.4 in | 56% | 75% | 6 mph | 9.3 h |
| April | 63°F | 56°F | 0.7 in | 52% | 76% | 7 mph | 8.0 h |
| May | 65°F | 58°F | 0.3 in | 59% | 78% | 6 mph | 6.8 h |
| June | 68°F | 60°F | 0.0 in | 68% | 79% | 5 mph | 6.2 h |
| July | 72°F | 64°F | 0.1 in | 63% | 77% | 5 mph | 6.5 h |
| August | 73°F | 65°F | 0.0 in | 55% | 76% | 5 mph | 7.6 h |
| September | 73°F | 65°F | 0.1 in | 48% | 75% | 5 mph | 8.8 h |
| October | 71°F | 63°F | 0.6 in | 48% | 72% | 5 mph | 9.9 h |
| November | 67°F | 59°F | 1.0 in | 48% | 67% | 6 mph | 10.7 h |
| December | 63°F | 55°F | 2.5 in | 52% | 67% | 6 mph | 11.1 h |
Climate averages: NASA POWER, 2001–2025, for the grid area around 33.50, -118.13 (about 50 km across). High and low temperatures are estimated from the monthly mean and the average daily range. Hills, coasts and cities can differ from the area average. Sources and methods.