Castolon, Texas climate: Climate normals at a NOAA weather station
Castolon's normal year runs from 36°F January nights to 104°F June afternoons, with 9.9 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 22.7°C, January lows of 2°C, June highs of 40°C, 250 mm of precipitation a year.
- NOAA stationCastolon
- Station IDUSC00411524
- Location29.13°N 103.51°W
- Elevation2,169 ft (661 m)
On October 23, the normal high in Castolon is 87°F and the normal low 56°F, and the chance of measurable rain or snow is 10%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Castolon.
- Jan 69° 36°
- Feb 75° 42°
- Mar 83° 48°
- Apr 92° 57°
- May 100° 67°
- Jun 104° 75°
- Jul 102° 75°
- Aug 102° 75°
- Sep 96° 70°
- Oct 89° 59°
- Nov 78° 46°
- Dec 69° 37°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Castolon each month?
June is the warmest month, with normal highs of 104°F; January the coldest, with normal lows of 36°F. The most precipitation falls in July (1.71 in), the least in December (0.28 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 69°F | 36°F | 52.4°F | 0.36 | 3 | <1 | 11 | 10 h 30 min |
| February | 75°F | 42°F | 58.5°F | 0.33 | 2 | 2 | 3 | 11 h 10 min |
| March | 83°F | 48°F | 65.8°F | 0.29 | 1 | 11 | 1 | 12 h |
| April | 92°F | 57°F | 74.6°F | 0.37 | 2 | 21 | <1 | 12 h 50 min |
| May | 100°F | 67°F | 83.4°F | 0.79 | 4 | 28 | <1 | 13 h 40 min |
| June | 104°F | 75°F | 89.4°F | 1.38 | 5 | 29 | <1 | 14 h |
| July | 102°F | 75°F | 88.8°F | 1.71 | 6 | 30 | <1 | 13 h 50 min |
| August | 102°F | 75°F | 88.5°F | 1.51 | 5 | 30 | <1 | 13 h 10 min |
| September | 96°F | 70°F | 82.9°F | 1.55 | 5 | 26 | <1 | 12 h 20 min |
| October | 89°F | 59°F | 74.2°F | 0.81 | 3 | 18 | <1 | 11 h 30 min |
| November | 78°F | 46°F | 61.6°F | 0.48 | 2 | 3 | 1 | 10 h 40 min |
| December | 69°F | 37°F | 52.9°F | 0.28 | 2 | <1 | 10 | 10 h 20 min |
| Year (annual) | 88°F | 57°F | 72.8°F | 9.86 | 40 | 197 | 25 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 21°C | 2°C | 11.3°C | 9 mm |
| February | 24°C | 5°C | 14.7°C | 8 mm |
| March | 29°C | 9°C | 18.8°C | 7 mm |
| April | 33°C | 14°C | 23.7°C | 9 mm |
| May | 38°C | 19°C | 28.6°C | 20 mm |
| June | 40°C | 24°C | 31.9°C | 35 mm |
| July | 39°C | 24°C | 31.6°C | 43 mm |
| August | 39°C | 24°C | 31.4°C | 38 mm |
| September | 36°C | 21°C | 28.3°C | 39 mm |
| October | 32°C | 15°C | 23.4°C | 21 mm |
| November | 25°C | 8°C | 16.4°C | 12 mm |
| December | 21°C | 3°C | 11.6°C | 7 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00411524; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
Which months are mildest at Castolon?
Normal highs sit between 65°F and 85°F in January, February, March, November and December. Of those, March has the fewest days with rain (1).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00411524.
When is the last frost at Castolon?
In Castolon, the last spring frost (32°F) comes after February 18 in half of years and after March 13 in one year in ten; the first autumn frost comes before November 29 in half of years and before November 13 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- February 181 year in 10 after March 13; 9 in 10 after January 25
- First autumn frost, half of years before
- November 291 year in 10 before November 13; 9 in 10 before December 20
NOAA puts the median frost-free season at 284 days, and the season without a hard freeze (28°F) at 315 days.
A hard freeze (28°F) comes after January 31 in half of springs and before December 11 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Castolon in zone 9a in ZIP code 79852, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 9a: the coldest night of a typical year reaches 22°F (17 complete years).
Frost dates for every NOAA station in Texas · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00411524; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get at Castolon?
In a normal year in Castolon, 197 days a year reach 90°F (109 of them 100°F or more), 25 nights fall to 32°F or colder and 40 days bring measurable precipitation.
- Days at 90°F or more
- 197a normal year
- Days at 100°F or more
- 109a normal year
- Nights at 32°F or colder
- 25a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 40a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00411524.
How sunny is it at Castolon?
Over a year 89% of the sunlight that would reach the ground under clear skies gets through the clouds at Castolon, 5.7 kWh per square metre a day. June is the sunniest month (92%) and January the cloudiest (85%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 85% | 3.8 |
| February | 87% | 4.8 |
| March | 89% | 6.0 |
| April | 90% | 7.0 |
| May | 91% | 7.5 |
| June | 92% | 7.6 |
| July | 87% | 7.0 |
| August | 88% | 6.6 |
| September | 87% | 5.7 |
| October | 90% | 5.1 |
| November | 89% | 4.1 |
| December | 87% | 3.6 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How many heating and cooling degree days does Castolon record?
A normal year at Castolon brings 1,239 heating degree days, 77% fewer than the median U.S. place (5,373), and 4,096 cooling degree days, 4.5 times the median (908). Two months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 8,473 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 392 | 2 |
| February | 203 | 21 |
| March | 86 | 111 |
| April | 12 | 300 |
| May | 1 | 573 |
| June | 0 | 732 |
| July | 0 | 738 |
| August | 0 | 727 |
| September | 1 | 538 |
| October | 18 | 303 |
| November | 151 | 50 |
| December | 376 | 3 |
| Year (annual) | 1,239 | 4,096 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00411524. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Have recent years at Castolon been warmer than normal?
2025 averaged 74.5°F, 1.7°F above the 1991-2020 normal of 72.8°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 73.0°F | +0.2°F | 6.39 |
| 2022 | 71.9°F | −0.9°F | 6.62 |
| 2023 | 73.8°F | +1.0°F | 7.61 |
| 2024 | 75.1°F | +2.3°F | 3.97 |
| 2025 | 74.5°F | +1.7°F | 4.19 |
Source: observed years: ACIS, station USC00411524. A year counts only with all twelve months complete.
How does Castolon's climate compare?
Castolon is warmer than 299 of the 321 places with their own NOAA record in Texas, and wetter than 5. Across the 7,247 U.S. stations with normals, its annual mean of 72.8°F is warmer than 97%.
In the Köppen classification computed from these normals, Castolon is BWh: hot desert. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Questions about Castolon's climate
What is the coldest month at Castolon?
January, with a normal high of 69°F and a normal low of 36°F. The warmest is June (104°F by day, 75°F at night).
Does it snow at Castolon?
Rarely: NOAA's normal is no measurable snow a year.
What is the rainiest month at Castolon?
July, with 1.71 in of precipitation in a normal year; the driest is December with 0.28 in.
What plant hardiness zone is Castolon in?
The USDA's 2023 map puts Castolon in zone 9a in ZIP code 79852, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches 22°F (17 years, 1991-2020): zone 9a.
How late can frost come at Castolon?
In half of years the last 32°F night comes after February 18; in one year in ten it comes after March 13. Waiting until March 13 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Texas climateThe statewide normals and every place in the state
- Study Butte, TX14 miles from this station, 71.1°F a year
- Terlingua, TX16 miles from this station, 70.3°F a year
- Chisos Basin, TX16 miles from this station, 62.9°F a year
- Lajitas, TX17 miles from this station, 70.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made