Photo: Larry D. Moore · CC BY 4.0San Marcos reaches 100° on about 21 days a year, more than 96% of U.S. towns
January nights here settle around 40°. The wettest month is May; the driest is February. Winters are mild: January nights here are milder than in 88% of U.S. towns. The outdoor season runs from February to April and October to December, with highs of 64–82°.
A year in San Marcos at a glance
Each month’s typical high and low, and what it brings.
What stands out about San Marcos’ climate
Compared with towns across the U.S., with San Marcos’ place in Texas beside it.
What a year in San Marcos feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 273 frost-free days a year
In half of years the last 32° night comes by February 28 and the first by November 29. Frost and day counts come from NOAA’s station at San Marcos, TX, 1.0 miles from the city’s center point, at about the same height.
The 2023 USDA map puts San Marcos’ center in zone 9a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 22°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 35 inches of rain a year
May is the wettest month and February the driest. Rain falls on about 80 days a year. Snow is rare: about 0.0" in a normal year at San Marcos, TX, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in San Marcos
35% of the work is heating, so air conditioning is the bigger bill. Months averaging under 55°: December and January.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at San Marcos, TX.
Living with San Marcos’ climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
273 frost-free days in zone 9a. The last frost comes by Feb 28 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Nov 29.
Months with highs of 62–84° and lows of 40° or more: February, March, April, October, November and December. 37 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in San Marcos from natural hazards, river flooding is the largest share (52%); heat waves, cold waves, winter storms and ice storms together are 12%. Normals are averages; the hazards page covers the extremes.
Natural hazards →San Marcos and its neighbors
Every town next door is within a degree of San Marcos in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like San Marcos’, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| San Marcos, TX | 40° | 96° | 35" | 0.0" |
| Chico, CA | 38° | 96° | 31" | 0.0" |
| Lone Grove, OK | 31° | 94° | 39" | 2.7" |
| Dublin, GA | 37° | 93° | 47" | 0.0" |
| Cayce, SC | 35° | 93° | 46" | 1.2" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
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°).
A smaller shift than in 52% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How San Marcos compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with San Marcos’ place among Texas’.
San Marcos weather by month
Highs, lows and precipitation from NOAA’s grid at San Marcos’ center; snow, wet days and snow on the ground from San Marcos, TX. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 63° | 40° | 2.4" | 0.0" | 7 | 0 | 46° – 56° |
| February | 67° | 44° | 1.9" | 0.0" | 7 | 0 | 47° – 63° |
| March | 73° | 51° | 2.8" | 0.0" | 8 | 0 | 56° – 67° |
| April | 80° | 57° | 2.7" | 0.0" | 7 | 0 | 63° – 74° |
| May | 87° | 65° | 4.3" | 0.0" | 8 | 0 | 71° – 81° |
| June | 93° | 71° | 3.4" | 0.0" | 6 | 0 | 79° – 86° |
| July | 96° | 73° | 2.2" | 0.0" | 5 | 0 | 80° – 88° |
| August | 97° | 73° | 2.4" | 0.0" | 5 | 0 | 80° – 89° |
| September | 91° | 68° | 3.5" | 0.0" | 7 | 0 | 76° – 85° |
| October | 82° | 58° | 4.0" | 0.0" | 6 | 0 | 67° – 75° |
| November | 72° | 49° | 2.6" | 0.0" | 6 | 0 | 54° – 65° |
| December | 64° | 41° | 2.5" | 0.0" | 8 | 0 | 46° – 56° |
| Year | 80° | 57° | 34.7" | 0.0" | 80 | 0 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 47° to 63°. June is the most reliable, staying within 8°.
Where San Marcos’ numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at San Marcos’ center.
- Snow: San Marcos, TX (NOAA station in town).
- Frost, freezing nights, 90° and 100° days, heating and cooling: San Marcos, TX, 1.0 miles from the city’s center point, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about San Marcos’ climate
What is the weather like in San Marcos?
A typical July afternoon reaches 96°, a January night drops to 40°, and snow is almost unheard of. Milder January nights than 88% of U.S. towns; hotter July afternoons than 96% of U.S. towns.
How cold does it get in San Marcos in winter?
January nights average 40°. About 20 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 46°.
How much snow does San Marcos get?
About 0.0 inches in a normal winter at San Marcos, TX, so most winters see none.
How hot does it get in San Marcos?
July, with a typical high of 96° and a low of 73°. About 117 days a year reach 90° and 21 reach 100° (San Marcos, TX).
When is the first and last frost in San Marcos?
In half of years the last spring frost (32°) comes by February 28 and the first fall frost by November 29, about 273 frost-free days, at San Marcos, TX.
What growing zone is San Marcos in?
Zone 9a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 22°.
What is the best time of year to visit San Marcos?
By one simple rule (highs of 62–84° and lows of 40° or more), February, March, April, October, November and December. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is San Marcos getting warmer?
Yes: 1991–2020 averaged 1.3° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 52% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in San Marcos.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.