San Juan, TX climate
San Juan has warm winters and hot summers, with very little rain. A typical July afternoon reaches 97°, a January night drops to 50°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in San Juan feels like
Winter
Spring
Summer
Fall
San Juan 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 | 71° | 50° | 0.8" | 0 | 3 | 0 | 54° – 67° |
| February | 76° | 54° | 0.8" | 0 | 3 | 0 | 57° – 73° |
| March | 82° | 60° | 1.2" | 0 | 4 | 0 | 65° – 77° |
| April | 87° | 65° | 1.5" | 0 | 4 | 0 | 70° – 81° |
| May | 92° | 71° | 2.2" | 0 | 3 | 0 | 77° – 85° |
| June | 96° | 75° | 2.8" | 0 | 4 | 0 | 83° – 89° |
| July | 97° | 76° | 2.2" | 0 | 3 | 0 | 83° – 90° |
| August | 99° | 76° | 1.7" | 0 | 4 | 0 | 85° – 90° |
| September | 93° | 73° | 4.7" | 0 | 6 | 0 | 80° – 86° |
| October | 88° | 66° | 2.4" | 0 | 4 | 0 | 75° – 81° |
| November | 79° | 58° | 1.3" | 0 | 3 | 0 | 63° – 75° |
| December | 73° | 52° | 1.1" | 0.1" | 3 | 0 | 56° – 67° |
| Year | 86° | 65° | 22.5" | 0.1" | 43 | 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 Juan
San Juan gets 22 inches of rain and melted snow a year. September is the wettest month and January the driest. Rain or snow falls on about 43 days a year.
A year-round growing season
Heating and cooling a home in San Juan
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In San Juan, 12% of that work is heating and 88% 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 Juan and its neighbors
San Juan borders 3 towns with climate data. January nights across them vary by 0.0°. North Alamo has the coldest January nights (50°) and Pharr the hottest July afternoons (97°). San Juan’s January low is 50° and its July high 97°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How San Juan 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 Juan averaged 1.2° warmer than the 1900s. The biggest change is in February (+2.0°). The shift is smaller than in 55% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at San Juan’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 57° to 73°. August is the most reliable, staying within 5°.
Common questions about San Juan’s climate
What is the coldest month in San Juan?
January, with a typical high of 71° and a low of 50°.
What is the hottest month in San Juan?
August, with a typical high of 99° and a low of 76°. About 170 days a year reach 90°.
How much snow does San Juan get?
Almost none. A normal year brings 0.1 inches.
When is the first frost in San Juan?
Frost is uncommon. Only 48% of years see a night at 32° or below.
What is the rainiest month in San Juan?
September, with 4.7 inches of rain and melted snow. The year totals 22 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for San Juan itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Mcallen, TX (6 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.