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San Marcos, California climate
BSh Hot semi-arid
San Marcos has a mildly seasonal warm-temperate climate (Hot semi-arid, Köppen BSh). The hottest month is August with an average daily high near 32°C, while the coldest is December averaging around 7°C at night. Precipitation totals about 369 mm a year and is strongly seasonal — February alone averages 91 mm while August barely receives 2 mm.
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figuresClear vs cloudy days
Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day countsSan Marcos climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 20 | 20 | 22 | 23 | 25 | 28 | 31 | 32 | 31 | 27 | 24 | 20 |
| Avg temp (°C) | 14 | 14 | 16 | 17 | 19 | 22 | 24 | 25 | 24 | 21 | 17 | 13 |
| Avg low (°C) | 7 | 8 | 9 | 11 | 14 | 16 | 18 | 19 | 17 | 14 | 10 | 7 |
| Precipitation (mm) | 81 | 91 | 56 | 25 | 9 | 2 | 3 | 2 | 4 | 14 | 27 | 54 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 20 | 20 | 22 | 23 | 25 | 28 |
| Avg temp (°C) | 14 | 14 | 16 | 17 | 19 | 22 |
| Avg low (°C) | 7 | 8 | 9 | 11 | 14 | 16 |
| Precipitation (mm) | 81 | 91 | 56 | 25 | 9 | 2 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 31 | 32 | 31 | 27 | 24 | 20 |
| Avg temp (°C) | 24 | 25 | 24 | 21 | 17 | 13 |
| Avg low (°C) | 18 | 19 | 17 | 14 | 10 | 7 |
| Precipitation (mm) | 3 | 2 | 4 | 14 | 27 | 54 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 6 | 6 | 5 | 4 | 2 | 0.9 | 0.7 | 0.4 | 0.9 | 2 | 3 | 6 |
| Days with high ≥ 32°C (days) | 0.0 | 0.1 | 0.5 | 1 | 2 | 4 | 9 | 12 | 10 | 5 | 1 | — |
| Days with low ≤ 0°C (days) | 0.6 | 0.2 | 0.0 | 0.0 | 0.1 | — | — | — | — | — | 0.1 | 0.5 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 6 | 6 | 5 | 4 | 2 | 0.9 |
| Days with high ≥ 32°C (days) | 0.0 | 0.1 | 0.5 | 1 | 2 | 4 |
| Days with low ≤ 0°C (days) | 0.6 | 0.2 | 0.0 | 0.0 | 0.1 | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 0.7 | 0.4 | 0.9 | 2 | 3 | 6 |
| Days with high ≥ 32°C (days) | 9 | 12 | 10 | 5 | 1 | — |
| Days with low ≤ 0°C (days) | — | — | — | — | 0.1 | 0.5 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 44 | 46 | 44 | 40 | 43 | 39 | 34 | 27 | 29 | 35 | 34 | 41 |
| Clear days (≤ 30% cloud) | 13 | 11 | 12 | 13 | 11 | 11 | 15 | 18 | 17 | 16 | 15 | 14 |
| Partly cloudy days (30–70%) | 9 | 9 | 12 | 11 | 15 | 15 | 14 | 12 | 10 | 10 | 10 | 9 |
| Cloudy days (≥ 70%) | 9 | 8 | 8 | 6 | 6 | 4 | 2 | 1.0 | 3 | 5 | 5 | 7 |
| Relative humidity (%) | 63 | 66 | 66 | 64 | 63 | 55 | 49 | 46 | 49 | 53 | 55 | 61 |
| Wind speed (m/s) | 2.3 | 2.4 | 2.4 | 2.7 | 2.7 | 2.5 | 2.3 | 2.1 | 2.0 | 2.1 | 2.2 | 2.3 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 44 | 46 | 44 | 40 | 43 | 39 |
| Clear days (≤ 30% cloud) | 13 | 11 | 12 | 13 | 11 | 11 |
| Partly cloudy days (30–70%) | 9 | 9 | 12 | 11 | 15 | 15 |
| Cloudy days (≥ 70%) | 9 | 8 | 8 | 6 | 6 | 4 |
| Relative humidity (%) | 63 | 66 | 66 | 64 | 63 | 55 |
| Wind speed (m/s) | 2.3 | 2.4 | 2.4 | 2.7 | 2.7 | 2.5 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 34 | 27 | 29 | 35 | 34 | 41 |
| Clear days (≤ 30% cloud) | 15 | 18 | 17 | 16 | 15 | 14 |
| Partly cloudy days (30–70%) | 14 | 12 | 10 | 10 | 10 | 9 |
| Cloudy days (≥ 70%) | 2 | 1.0 | 3 | 5 | 5 | 7 |
| Relative humidity (%) | 49 | 46 | 49 | 53 | 55 | 61 |
| Wind speed (m/s) | 2.3 | 2.1 | 2.0 | 2.1 | 2.2 | 2.3 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Escondido #2 (NOAA GHCN station USC00042863), about 8 km from the city centre.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.