USDA Hardiness Zone 10a
Frost Dates for 78583 — Rio Hondo, Texas
NOAA 1991–2020 normals from Harlingen Rio Grande Airport, TX (34 ft), 8 miles west.
Updated
A freeze (32°F) reaches Rio Hondo in 61% of winters. When it does, the first fall frost comes around December 29 and the last spring frost around January 8; after February 17 the chance of another is under 6%.
- Last spring frost
- January 8
- First fall frost
- December 29
- Winters with a freeze
- 61%
- Hardiness zone
- 10a
50%, in freezing years
50%, in freezing years
32°F or below, 1991–2020
30 to 35°F (-1.1 to 1.7°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 5%
- Snow per year
- 0.1"
median, 1991–2020
median, 1991–2020
1 of 20 observed
NOAA normal
Frost risk by date in Rio Hondo
In the 61% of winters that bring a 32°F night, half of springs at Harlingen Rio Grande Airport, TX see their last 32°F night by January 8; only one in ten is past it by December 12, and one in ten still has one after February 17. Counting the winters with no freeze at all, the risk of a 32°F night after February 17 is under 6% and after January 8 30%. The 40 days between the even-odds date and the one-in-ten date is wider than at 99% of the 339 Texas stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.
In fall the first 32°F night comes by December 29 in half of years, as early as December 2 one year in ten, and holds off past February 1 one year in ten. A hard freeze of 28°F is less common: it came in 18% of winters. The freeze-free season lasts 357 days in a typical year, longer than at 100% of the 339 Texas stations; it reaches 365 days one year in ten and falls short of 314 one year in ten. On average 2 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 23 days longer, to about January 31, and return around December 13. A 24°F night is unusual: 2% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F96% of yrs | Dec 28 | Jan 8 | Jan 16 | Jan 25 | Jan 31 | Feb 6 | Feb 16 | Feb 23 | Mar 3 |
| 32°F61% of yrs | Dec 12 | Dec 23 | Dec 30 | Jan 4 | Jan 8 | Jan 16 | Jan 27 | Feb 3 | Feb 17 |
| 28°F18% of yrs | too rare for a date | ||||||||
| 24°F2% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F96% of yrs | Nov 18 | Nov 27 | Dec 2 | Dec 8 | Dec 13 | Dec 20 | Dec 26 | Jan 4 | Jan 15 |
| 32°F61% of yrs | Dec 2 | Dec 10 | Dec 18 | Dec 24 | Dec 29 | Jan 2 | Jan 7 | Jan 16 | Feb 1 |
| 28°F18% of yrs | too rare for a date | ||||||||
| 24°F2% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Harlingen Rio Grande Airport, TX, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 78583 →Compare Rio Hondo with another place →
Weather by month in Rio Hondo
August is the warmest month at Harlingen Rio Grande Airport, TX, averaging 97°F by day and 75°F at night; January is the coldest at 72°F and 50°F. From March to November the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 14% of years.
Warmth for growing adds up to 9,166 growing degree days a year (base 50°F), more than at 98% of the 351 Texas stations. 46% of them (4,190) have built up by the end of June, and August adds the most, 1,124. Precipitation totals 24.1 inches a year, most in September (5.3") and least in February (0.7"); May to September bring 57% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 72 | 50 | 1.1 | 32% | 1 | 353 |
| Feb | 76 | 54 | 0.7 | 14% | <1 | 424 |
| Mar | 81 | 59 | 1.3 | 2% | 0 | 627 |
| Apr | 87 | 65 | 1.5 | 0% | 0 | 776 |
| May | 91 | 71 | 2.5 | 0% | 0 | 967 |
| Jun | 95 | 75 | 2.3 | 0% | 0 | 1044 |
| Jul | 96 | 75 | 1.8 | 0% | 0 | 1108 |
| Aug | 97 | 75 | 1.9 | 0% | 0 | 1124 |
| Sep | 92 | 73 | 5.3 | 0% | 0 | 971 |
| Oct | 88 | 66 | 2.7 | 0% | 0 | 825 |
| Nov | 79 | 57 | 1.8 | 5% | 0 | 553 |
| Dec | 73 | 52 | 1.2 | 29% | 1 | 396 |
Monthly normals 1991–2020 at Harlingen Rio Grande Airport, TX (34 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Harlingen, TX, 10 miles southwest of Rio Hondo, has a 32°F night in 31% of winters against 61% here, and a coolest-month low 1°F warmer (51°F).
When it snows in Rio Hondo, Texas
Measurable snow is rare here: only 1 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Harlingen, TX, 9.7 miles away, so there is no typical first-snow date to plan around.
Where these figures come from
ZIP 78583 is 8 miles from Harlingen Rio Grande Airport, TX, which stands at 34 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 78583 in zone 10a, the band where the coldest night of the year averaged 30 to 35°F (-1.1 to 1.7°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.