Climate averages 1991–2020
Mission Viejo weather
in December.
A mild, moderately wet month: the coolest and the 10th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a mild month in Mission Viejo: daytime highs average 17.6°C and nights cool to about 8.5°C. By daytime temperature it is the coolest month of the year.
Expect about 48 mm of rain on roughly 5 days, which makes December a moderately wet month (the 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 9 h 58 min on an average December day.
The nearest other city in this atlas is Irvine (16 km away). In December its highs average 18.2°C, 0.5°C warmer than Mission Viejo, with 55 mm of rain.
Among the 498 cities listed in the United States, Mission Viejo ranks joint 79th of 498 for the warmest December highs and joint 122nd of 498 for the driest December (rainfall, lowest first). The mean December high of those 498 cities is 10.5°C; Mission Viejo is 7.1°C warmer than that mean.
From December to January, average highs rise by 0.1°C to 17.8°C, and monthly rainfall rises from 48 mm to 66 mm.
The annual picture
December in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Mission Viejo climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 17.8°C8.4°C | 8.4°C | 66 | 5.5 | 10.210 h |
| February | 17.7°C8.9°C | 8.9°C | 79 | 6.3 | 11.011 h |
| March | 18.5°C10.1°C | 10.1°C | 46 | 5.7 | 12.012 h |
| April | 19.8°C11.4°C | 11.4°C | 20 | 2.9 | 13.013 h |
| May | 21.0°C13.4°C | 13.4°C | 7.7 | 1.7 | 13.914 h |
| June | 23.4°C15.3°C | 15.3°C | 1.5 | 0.4 | 14.314 h |
| July | 26.1°C17.7°C | 17.7°C | 1.3 | 0.4 | 14.114 h |
| August | 27.2°C18.5°C | 18.5°C | 0.8 | 0.2 | 13.413 h |
| September | 26.6°C17.9°C | 17.9°C | 3.3 | 0.6 | 12.412 h |
| October | 24.1°C15.1°C | 15.1°C | 15 | 2.0 | 11.411 h |
| November | 21.0°C11.6°C | 11.6°C | 21 | 2.7 | 10.510 h |
| December, selected | 17.6°C8.5°C | 8.5°C | 48 | 4.9 | 10.010 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
December in nearby cities
- Irvine in DecemberUnited States · 16 kmHigh 18.2°C · Low 8.4°C · 55 mm rain
- Santa Ana, United States in DecemberUnited States · 24 kmHigh 17.4°C · Low 8.1°C · 55 mm rain
- Huntington Beach in DecemberUnited States · 31 kmHigh 17.4°C · Low 8.1°C · 48 mm rain
- Corona in DecemberUnited States · 32 kmHigh 18.0°C · Low 5.6°C · 67 mm rain
- Anaheim in DecemberUnited States · 34 kmHigh 17.9°C · Low 6.6°C · 48 mm rain
- Westminster (California), United States in DecemberUnited States · 36 kmHigh 17.9°C · Low 7.0°C · 48 mm rain
- Fullerton in DecemberUnited States · 38 kmHigh 18.4°C · Low 6.5°C · 48 mm rain
- Buena Park in DecemberUnited States · 42 kmHigh 18.5°C · Low 6.4°C · 48 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Mission Viejo) is explained once on the Mission Viejo year overview and on the Sources, method and limits page.