Climate averages 1991–2020
San Marcos weather
in January.
A mild, moderately wet month: the 10th warmest and the 11th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
January is a mild month in San Marcos: daytime highs average 16.8°C and nights cool to about 6.1°C. By daytime temperature it is the 10th warmest of the 12 months.
Expect about 73 mm of rain on roughly 6 days, which makes January a moderately wet month (the 11th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 10 h 14 min on an average January day.
The nearest other city in this atlas is Escondido (8 km away). In January its highs average 17.7°C, 0.9°C warmer than San Marcos, with 75 mm of rain.
Among the 498 cities listed in the United States, San Marcos ranks joint 105th of 498 for the warmest January highs and joint 241st of 498 for the driest January (rainfall, lowest first). The mean January high of those 498 cities is 9.5°C; San Marcos is 7.4°C warmer than that mean.
From January to February, average highs fall by 0.1°C to 16.7°C, and monthly rainfall rises from 73 mm to 92 mm.
The annual picture
January 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
San Marcos climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January, selected | 16.8°C6.1°C | 6.1°C | 73 | 5.8 | 10.210 h |
| February | 16.7°C6.9°C | 6.9°C | 92 | 6.8 | 11.011 h |
| March | 17.6°C8.5°C | 8.5°C | 57 | 6.2 | 12.012 h |
| April | 19.1°C10.3°C | 10.3°C | 28 | 4.1 | 13.013 h |
| May | 20.7°C12.7°C | 12.7°C | 13 | 2.1 | 13.814 h |
| June | 23.2°C14.8°C | 14.8°C | 2.5 | 0.5 | 14.314 h |
| July | 25.8°C17.2°C | 17.2°C | 2.0 | 0.4 | 14.114 h |
| August | 26.9°C18.2°C | 18.2°C | 1.0 | 0.2 | 13.413 h |
| September | 26.2°C17.3°C | 17.3°C | 3.9 | 0.7 | 12.412 h |
| October | 23.3°C13.7°C | 13.7°C | 17 | 2.6 | 11.411 h |
| November | 20.0°C9.4°C | 9.4°C | 28 | 3.5 | 10.510 h |
| December | 16.7°C6.2°C | 6.2°C | 54 | 5.1 | 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
January in nearby cities
- Escondido in JanuaryUnited States · 8 kmHigh 17.7°C · Low 5.7°C · 75 mm rain
- Vista in JanuaryUnited States · 10 kmHigh 17.8°C · Low 6.5°C · 73 mm rain
- Oceanside in JanuaryUnited States · 21 kmHigh 16.9°C · Low 8.3°C · 62 mm rain
- Temecula in JanuaryUnited States · 39 kmHigh 18.3°C · Low 5.5°C · 70 mm rain
- El Cajon in JanuaryUnited States · 43 kmHigh 17.9°C · Low 7.9°C · 57 mm rain
- Murrieta in JanuaryUnited States · 46 kmHigh 17.9°C · Low 5.0°C · 70 mm rain
- San Diego in JanuaryUnited States · 48 kmHigh 17.4°C · Low 8.7°C · 50 mm rain
- Chula Vista in JanuaryUnited States · 56 kmHigh 17.1°C · Low 9.3°C · 57 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 San Marcos) is explained once on the San Marcos year overview and on the Sources, method and limits page.
Vista lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.