San Isidro reaches 100° on about 47 days a year, more than all but 160 U.S. towns
The coldest hours of a January night bottom out at 48° on average. Seasons differ by 51°, from the coldest nights to the warmest afternoons. By January nights alone, it runs milder than 96% of U.S. towns. For walks and days out, the stretch from November to March brings highs of 70–81°.
A year in San Isidro at a glance
Each month’s typical high and low, and what it brings.
What stands out about San Isidro’s climate
Compared with towns across the U.S., with San Isidro’s place in Texas beside it.
What a year in San Isidro feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 47 days a year reach 100°
And 170 days reach 90°. Frost and day counts come from NOAA’s station at Mccook, TX, 22 miles from the town’s center, at about the same height.
The 2023 USDA map puts San Isidro’s center in zone 9b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 29°. 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 24 inches of rain a year
September is the wettest month and February the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in San Isidro
17% of the work is heating, so air conditioning is the bigger bill. No month averages under 55°.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Mccook, TX.
Living with San Isidro’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 9b. Frost comes about 9 winters in 10, so the growing year is set by heat, not cold: 47 days at 100° make midsummer the hard season for gardens.
Months with highs of 62–84° and lows of 40° or more: January, February, March, November and December. 2.4 miles of trails are waiting.
Parks & trails →Cold waves are 41% of the yearly building losses FEMA expects in San Isidro from natural hazards, the largest share. Normals are averages; the hazards page covers the extremes.
Natural hazards →San Isidro and similar climates
TownRatings has no climate map of the towns around San Isidro yet.
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
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°).
A bigger shift than in 60% 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 Isidro compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with San Isidro’s place among Texas’.
San Isidro weather by month
Highs, lows and precipitation from NOAA’s grid at San Isidro’s center. 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" |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 56° to 71°. August is the most reliable, staying within 5°.
Where San Isidro’s 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 Isidro’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Mccook, TX, 22 miles from the town’s center, 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 Isidro’s climate
What is the weather like in San Isidro?
A typical July afternoon reaches 98°, a January night drops to 48°. Milder January nights than 96% of U.S. towns; hotter July afternoons than 98% of U.S. towns.
How cold does it get in San Isidro in winter?
January nights average 48°. About 3 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 52°.
How hot does it get in San Isidro?
July, with a typical high of 98° and a low of 75°. About 170 days a year reach 90° and 47 reach 100° (Mccook, TX).
When is the first and last frost in San Isidro?
There is no reliable frost date: a 32° night comes in about 86% of winters at Mccook, TX, so most years bring a freeze but some pass without one.
What growing zone is San Isidro in?
Zone 9b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 29°.
What is the best time of year to visit San Isidro?
By one simple rule (highs of 62–84° and lows of 40° or more), January, February, March, November and December. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is San Isidro getting warmer?
Yes: 1991–2020 averaged 1.5° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 60% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in San Isidro.
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.