Weather and climate in Walnut, CA
What the weather is like in Walnut
The warmest month in Walnut is August, with average highs of 86°F. The coolest is December, when nights average 44°F. About 13.0 in of rain and snow falls in a typical year, most in February and least in June.
Skies are clearest in August (14% average cloud cover) and cloudiest in January (42%). Combining cloud with the length of truly dark nights, October, September, November 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 | 44°F | 2.9 in | 42% | 59% | 5 mph | 10.9 h |
| February | 63°F | 45°F | 2.9 in | 42% | 63% | 5 mph | 10.2 h |
| March | 67°F | 47°F | 1.6 in | 40% | 64% | 5 mph | 9.2 h |
| April | 69°F | 49°F | 0.7 in | 35% | 63% | 5 mph | 8.0 h |
| May | 74°F | 53°F | 0.3 in | 29% | 62% | 5 mph | 6.8 h |
| June | 80°F | 57°F | 0.0 in | 21% | 57% | 4 mph | 6.1 h |
| July | 85°F | 63°F | 0.1 in | 17% | 52% | 4 mph | 6.5 h |
| August | 86°F | 64°F | 0.0 in | 14% | 49% | 4 mph | 7.6 h |
| September | 84°F | 62°F | 0.1 in | 17% | 50% | 4 mph | 8.8 h |
| October | 78°F | 57°F | 0.7 in | 25% | 52% | 4 mph | 9.9 h |
| November | 70°F | 50°F | 1.0 in | 33% | 53% | 5 mph | 10.7 h |
| December | 62°F | 44°F | 2.6 in | 42% | 58% | 5 mph | 11.1 h |
Climate nearby
Climate averages: NASA POWER, 2001–2025, for the grid area around 34.00, -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.