San Isidro, TX climate
San Isidro has warm winters and hot summers. A typical July afternoon reaches 98°, a January night drops to 48°.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in San Isidro feels like
Winter
Spring
Summer
Fall
San Isidro weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 70° | 48° | 1.0" | 52° – 65° |
| February | 75° | 52° | 0.9" | 56° – 71° |
| March | 81° | 58° | 1.4" | 63° – 76° |
| April | 87° | 64° | 1.5" | 70° – 80° |
| May | 92° | 70° | 2.6" | 76° – 84° |
| June | 97° | 74° | 2.7" | 83° – 89° |
| July | 98° | 75° | 2.2" | 83° – 90° |
| August | 99° | 75° | 2.0" | 85° – 90° |
| September | 93° | 72° | 4.6" | 79° – 85° |
| October | 87° | 65° | 2.2" | 73° – 80° |
| November | 78° | 56° | 1.5" | 61° – 73° |
| December | 71° | 49° | 1.1" | 54° – 65° |
| Year | 86° | 63° | 23.8" |
“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 Isidro
San Isidro gets 24 inches of rain and melted snow a year. September is the wettest month and February the driest.
A year-round growing season
Heating and cooling a home in San Isidro
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In San Isidro, 17% of that work is heating and 83% 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.
How San Isidro 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 Isidro averaged 1.5° warmer than the 1900s. The biggest change is in February (+2.5°). The shift is larger than in 70% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at San Isidro’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 56° to 71°. August is the most reliable, staying within 5°.
Common questions about San Isidro’s climate
What is the coldest month in San Isidro?
January, with a typical high of 70° and a low of 48°.
What is the hottest month in San Isidro?
August, with a typical high of 99° and a low of 75°. About 170 days a year reach 90°.
When is the first frost in San Isidro?
Frost is uncommon. Only 86% of years see a night at 32° or below.
What is the rainiest month in San Isidro?
September, with 4.6 inches of rain and melted snow. The year totals 24 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for San Isidro itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Mccook, TX (22 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.