San Marcos, TX climate
San Marcos has mild winters and hot summers. A typical July afternoon reaches 96°, a January night drops to 40°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in San Marcos feels like
Winter
Spring
Summer
Fall
San Marcos weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 63° | 40° | 2.4" | 0 | 7 | 0 | 46° – 56° |
| February | 67° | 44° | 1.9" | 0 | 7 | 0 | 47° – 63° |
| March | 73° | 51° | 2.8" | 0 | 8 | 0 | 56° – 67° |
| April | 80° | 57° | 2.7" | 0 | 7 | 0 | 63° – 74° |
| May | 87° | 65° | 4.3" | 0 | 8 | 0 | 71° – 81° |
| June | 93° | 71° | 3.4" | 0 | 6 | 0 | 79° – 86° |
| July | 96° | 73° | 2.2" | 0 | 5 | 0 | 80° – 88° |
| August | 97° | 73° | 2.4" | 0 | 5 | 0 | 80° – 89° |
| September | 91° | 68° | 3.5" | 0 | 7 | 0 | 76° – 85° |
| October | 82° | 58° | 4.0" | 0 | 6 | 0 | 67° – 75° |
| November | 72° | 49° | 2.6" | 0 | 6 | 0 | 54° – 65° |
| December | 64° | 41° | 2.5" | 0 | 8 | 0 | 46° – 56° |
| Year | 80° | 57° | 34.7" | 0.0" | 80 | 0 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in San Marcos
San Marcos gets 35 inches of rain and melted snow a year. May is the wettest month and February the driest. Rain or snow falls on about 80 days a year.
About 273 frost-free days a year
In half of years the last 32° night comes by February 28 and the first one by November 29. That leaves about 273 frost-free days for gardens, longer than 93% of U.S. towns.
Heating and cooling a home in San Marcos
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In San Marcos, 35% of that work is heating and 65% is cooling, so air conditioning is the bigger bill.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
San Marcos and its neighbors
San Marcos borders 2 towns with climate data. January nights across them vary by 0.5°. Kyle has both the coldest January nights (39°) and the hottest July afternoons (96°). San Marcos’s January low is 40° and its July high 96°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How San Marcos compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in San Marcos averaged 1.3° warmer than the 1900s. The biggest change is in February (+2.2°). The shift is larger than in 59% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at San Marcos’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 47° to 63°. June is the most reliable, staying within 8°.
Common questions about San Marcos’s climate
What is the coldest month in San Marcos?
January, with a typical high of 63° and a low of 40°.
What is the hottest month in San Marcos?
August, with a typical high of 97° and a low of 73°. About 117 days a year reach 90°.
How much snow does San Marcos get?
Almost none. A normal year brings 0.0 inches.
When is the first frost in San Marcos?
In half of years the first 32° night comes by November 29, and the last spring frost by February 28.
What is the rainiest month in San Marcos?
May, with 4.3 inches of rain and melted snow. The year totals 35 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for San Marcos itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at San Marcos, TX (1 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.