Port Isabel, Texas climate: Normal weather by month, frost dates and records
Port Isabel's normal year runs from 52°F January nights to 93°F August afternoons, with 23.3 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 23.8°C, January lows of 11°C, August highs of 34°C, 591 mm of precipitation a year.
- NOAA stationPort Isabel Cameron Airport
- Station IDUSW00012957
- Location26.17°N 97.35°W
- Elevation19 ft (6 m)
- Population5,210
On October 23, the normal high in Port Isabel is 84°F and the normal low 67°F, and the chance of measurable rain or snow is 24%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Port Isabel.
- Jan 70° 52°
- Feb 74° 56°
- Mar 78° 62°
- Apr 83° 68°
- May 88° 73°
- Jun 92° 77°
- Jul 92° 78°
- Aug 93° 77°
- Sep 90° 75°
- Oct 85° 69°
- Nov 78° 61°
- Dec 72° 54°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Port Isabel each month?
August is the warmest month, with normal highs of 93°F; January the coldest, with normal lows of 52°F. The most precipitation falls in September (5.26 in), the least in January (0.96 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 70°F | 52°F | 61.1°F | 0.96 | 8 | <1 | 1 | 10 h 40 min |
| February | 74°F | 56°F | 64.8°F | 1.16 | 6 | <1 | <1 | 11 h 20 min |
| March | 78°F | 62°F | 69.8°F | 1.11 | 5 | 1 | <1 | 12 h |
| April | 83°F | 68°F | 75.2°F | 1.28 | 4 | 4 | <1 | 12 h 50 min |
| May | 88°F | 73°F | 80.6°F | 2.13 | 4 | 12 | <1 | 13 h 20 min |
| June | 92°F | 77°F | 84.2°F | 2.68 | 5 | 23 | <1 | 13 h 50 min |
| July | 92°F | 78°F | 85.1°F | 1.44 | 5 | 27 | <1 | 13 h 40 min |
| August | 93°F | 77°F | 85.4°F | 1.33 | 4 | 29 | <1 | 13 h 10 min |
| September | 90°F | 75°F | 82.6°F | 5.26 | 10 | 18 | <1 | 12 h 20 min |
| October | 85°F | 69°F | 76.9°F | 2.73 | 7 | 7 | <1 | 11 h 30 min |
| November | 78°F | 61°F | 69.4°F | 1.91 | 8 | <1 | <1 | 10 h 50 min |
| December | 72°F | 54°F | 63.0°F | 1.26 | 7 | <1 | <1 | 10 h 30 min |
| Year (annual) | 83°F | 67°F | 74.8°F | 23.25 | 73 | 121 | 1 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 21°C | 11°C | 16.2°C | 24 mm |
| February | 23°C | 13°C | 18.2°C | 29 mm |
| March | 26°C | 16°C | 21.0°C | 28 mm |
| April | 28°C | 20°C | 24.0°C | 33 mm |
| May | 31°C | 23°C | 27.0°C | 54 mm |
| June | 33°C | 25°C | 29.0°C | 68 mm |
| July | 34°C | 25°C | 29.5°C | 37 mm |
| August | 34°C | 25°C | 29.7°C | 34 mm |
| September | 32°C | 24°C | 28.1°C | 134 mm |
| October | 30°C | 20°C | 24.9°C | 69 mm |
| November | 26°C | 16°C | 20.8°C | 49 mm |
| December | 22°C | 12°C | 17.2°C | 32 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00012957; 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.
When is the best weather to visit Port Isabel?
Normal highs sit between 65°F and 85°F in January, February, March, April, November and December. Of those, April has the fewest days with rain (4).
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 USW00012957.
When is the last frost in Port Isabel?
A night at 32°F or colder comes in only 35% of years in Port Isabel (NOAA). NOAA's median date of the last spring frost is January 8 and of the first autumn frost January 4.
NOAA puts the median frost-free season at 365 days, and the season without a hard freeze (28°F) at 365 days.
The USDA's 2023 Plant Hardiness Zone Map puts Port Isabel in zone 10a in ZIP code 78578. By the map's own method, the average of each year's coldest night over 1991-2020, Port Isabel's NOAA station is in zone 10a: the coldest night of a typical year reaches 34°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 USW00012957; 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 in Port Isabel?
In a normal year in Port Isabel, 121 days a year reach 90°F (1 of them 100°F or more), 1 night falls to 32°F or colder and 73 days bring measurable precipitation.
- Days at 90°F or more
- 121a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 1a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 73a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USW00012957.
How sunny is Port Isabel?
Over a year 79% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Port Isabel, 4.8 kWh per square metre a day. August is the sunniest month (87%) and December the cloudiest (68%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 69% | 3.1 |
| February | 70% | 3.7 |
| March | 73% | 4.6 |
| April | 77% | 5.4 |
| May | 82% | 6.0 |
| June | 86% | 6.5 |
| July | 86% | 6.5 |
| August | 87% | 6.2 |
| September | 80% | 5.2 |
| October | 83% | 4.6 |
| November | 76% | 3.5 |
| December | 68% | 2.8 |
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 much heating and cooling does Port Isabel need?
A normal year in Port Isabel brings 527 heating degree days, 90% fewer than the median U.S. place (5,373), and 4,140 cooling degree days, 4.6 times the median (908). No month reaches 300 heating degree days. For gardens and crops, NOAA counts 9,122 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 177 | 55 |
| February | 103 | 96 |
| March | 39 | 189 |
| April | 7 | 314 |
| May | 0 | 484 |
| June | 0 | 577 |
| July | 0 | 623 |
| August | 0 | 632 |
| September | 0 | 529 |
| October | 4 | 374 |
| November | 50 | 180 |
| December | 147 | 85 |
| Year (annual) | 527 | 4,140 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00012957. 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.
Has Port Isabel been warmer than normal lately?
2025 averaged 75.9°F, 1.1°F above the 1991-2020 normal of 74.8°F. 3 of the 4 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2022 | 74.5°F | −0.3°F | – |
| 2023 | 76.7°F | +1.9°F | 24.33 |
| 2024 | 76.6°F | +1.8°F | 33.50 |
| 2025 | 75.9°F | +1.1°F | 21.86 |
Source: observed years: ACIS, station USW00012957. A year counts only with all twelve months complete.
How does Port Isabel's climate compare?
Port Isabel is warmer than 315 of the other 320 places with their own NOAA record in Texas, and wetter than 91. Across the 7,247 U.S. stations with normals, its annual mean of 74.8°F is warmer than 99%.
In the Köppen classification computed from these normals, Port Isabel is BSh: hot semi-arid steppe. 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.
Which places near Port Isabel share this climate record?
10 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Los Fresnos, TX8,563 people · 11 mi SW
- Laguna Vista, TX3,791 people · 5 mi SE
- Laureles, TX3,505 people · 9 mi W
- Laguna Heights, TX990 people · 8 mi SE
- Indian Lake, TX888 people · 11 mi SW
- Orason, TX697 people · 9 mi SW
- Bayview, TX555 people · 4 mi SW
- La Tina Ranch, TX427 people · 9 mi W
- Chula Vista, TX203 people · 9 mi SW
- Del Mar Heights, TX102 people · 9 mi SW
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Port Isabel's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Port Isabel. This page uses Port Isabel Cameron Airport; the other differs by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Port Isabel station USC00417179 | 5 mi SE | 17 ft | 74.0°F | 52°F | 91°F | 28.8 | 0 | January 3 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Port Isabel's climate
What is the coldest month in Port Isabel?
January, with a normal high of 70°F and a normal low of 52°F. The warmest is August (93°F by day, 77°F at night).
Does it snow in Port Isabel?
Rarely. NOAA publishes no 1991-2020 snowfall normal for Port Isabel's NOAA station; Port Isabel's own co-op station Port Isabel station records 0 inches of snow in a normal year.
What is the rainiest month in Port Isabel?
September, with 5.26 in of precipitation in a normal year; the driest is January with 0.96 in.
What plant hardiness zone is Port Isabel in?
The USDA's 2023 map puts Port Isabel in zone 10a in ZIP code 78578. By the same method at Port Isabel's NOAA station, the coldest night of a typical year reaches 34°F (17 years, 1991-2020): zone 10a.
Nearby and next
- Texas climateThe statewide normals and every place in the state
- South Padre Island, TX16 miles from this station, 74.7°F a year
- Brownsville, TX18 miles from this station, 76.2°F a year
- Harlingen, TX20 miles from this station, 74.9°F a year
- Port Mansfield, TX27 miles from this station, 73.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made