Climate averages 1991–2020
San Marcos weather
in May.
A mild, very dry month: the 6th warmest and the 5th driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
May is a mild month in San Marcos: daytime highs average 20.7°C and nights cool to about 12.7°C. By daytime temperature it is the 6th warmest of the 12 months.
Expect about 13 mm of rain on roughly 2 days, which makes May a very dry month (the 5th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 51 min on an average May day.
The nearest other city in this atlas is Escondido (8 km away). In May its highs average 22.2°C, 1.6°C warmer than San Marcos, with 16 mm of rain.
Among the 498 cities listed in the United States, San Marcos ranks joint 348th of 498 for the warmest May highs and joint 70th of 498 for the driest May (rainfall, lowest first). The mean May high of those 498 cities is 23.8°C; San Marcos is 3.1°C cooler than that mean.
From May to June, average highs rise by 2.5°C to 23.2°C, and monthly rainfall falls from 13 mm to 2.5 mm.
The annual picture
May 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 | 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, selected | 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
May in nearby cities
- Escondido in MayUnited States · 8 kmHigh 22.2°C · Low 12.6°C · 16 mm rain
- Vista in MayUnited States · 10 kmHigh 22.0°C · Low 13.2°C · 13 mm rain
- Oceanside in MayUnited States · 21 kmHigh 19.9°C · Low 13.7°C · 7.5 mm rain
- Temecula in MayUnited States · 39 kmHigh 24.7°C · Low 12.3°C · 11 mm rain
- El Cajon in MayUnited States · 43 kmHigh 21.7°C · Low 13.0°C · 10 mm rain
- Murrieta in MayUnited States · 46 kmHigh 24.7°C · Low 12.7°C · 11 mm rain
- San Diego in MayUnited States · 48 kmHigh 20.2°C · Low 13.6°C · 7.1 mm rain
- Chula Vista in MayUnited States · 56 kmHigh 19.4°C · Low 13.6°C · 10 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.