USDA Hardiness Zone 7b
Frost Dates for 74437 — Henryetta, Oklahoma
NOAA 1991–2020 normals from Okmulgee Wtr Wks, OK (647 ft), 13 miles north.
Updated
In Henryetta, the last spring frost (32°F) is around April 8 in half of years and has passed by April 25 in nine years out of ten. The first fall frost comes around October 28, as early as October 12 one year in ten, leaving a typical freeze-free season of 203 days (NOAA, Okmulgee Wtr Wks, OK).
- Last spring frost
- April 8
- First fall frost
- October 28
- Growing season
- 203 days
- Hardiness zone
- 7b
50% probability
50% probability
freeze-free, 50%
5 to 10°F (-15.0 to -12.2°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 24%
- Snow per year
- 0.9"
median, 1991–2020
median, 1991–2020
4 of 17 observed
NOAA normal
Frost risk by date in Henryetta
Half of springs at Okmulgee Wtr Wks, OK see their last 32°F night by April 8; only one in ten is past it by March 23, and one in ten still has one after April 25. Planting tender crops after April 14 leaves a 30% risk of a frost on them, after April 20 20%, and after April 25 10%. The 17 days between the even-odds date and the one-in-ten date is narrower than at 41% of the 114 Oklahoma stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 28 in half of years, as early as October 12 one year in ten, and holds off past November 11 one year in ten. A hard freeze of 28°F follows 9 days later, around November 6; in spring the one-in-ten date for 28°F is April 15, 10 days before the 32°F one. The freeze-free season lasts 203 days in a typical year, shorter than at 81% of the 114 Oklahoma stations; it reaches 224 days one year in ten and falls short of 181 one year in ten. On average 87 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 11 days longer, to about April 19, and return around October 20. Severe cold of 16°F or below comes every winter, usually between December 11 and February 23.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Mar 31 | Apr 8 | Apr 12 | Apr 15 | Apr 19 | Apr 23 | Apr 25 | Apr 29 | May 3 |
| 32°F | Mar 23 | Mar 28 | Apr 1 | Apr 5 | Apr 8 | Apr 11 | Apr 14 | Apr 20 | Apr 25 |
| 28°F | Mar 11 | Mar 16 | Mar 21 | Mar 25 | Mar 29 | Apr 1 | Apr 5 | Apr 8 | Apr 15 |
| 24°F | Feb 28 | Mar 4 | Mar 8 | Mar 12 | Mar 15 | Mar 19 | Mar 23 | Mar 27 | Apr 3 |
| 20°F | Feb 15 | Feb 23 | Feb 27 | Mar 1 | Mar 4 | Mar 6 | Mar 10 | Mar 14 | Mar 19 |
| 16°F | Jan 25 | Feb 5 | Feb 13 | Feb 19 | Feb 23 | Feb 28 | Mar 2 | Mar 5 | Mar 11 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 5 | Oct 9 | Oct 13 | Oct 17 | Oct 20 | Oct 22 | Oct 25 | Oct 29 | Nov 2 |
| 32°F | Oct 12 | Oct 19 | Oct 23 | Oct 26 | Oct 28 | Oct 31 | Nov 3 | Nov 6 | Nov 11 |
| 28°F | Oct 22 | Oct 28 | Oct 31 | Nov 3 | Nov 6 | Nov 9 | Nov 13 | Nov 18 | Nov 23 |
| 24°F | Oct 31 | Nov 5 | Nov 9 | Nov 12 | Nov 17 | Nov 22 | Nov 25 | Nov 30 | Dec 4 |
| 20°F | Nov 8 | Nov 15 | Nov 21 | Nov 25 | Nov 29 | Dec 2 | Dec 5 | Dec 10 | Dec 16 |
| 16°F | Nov 21 | Nov 28 | Dec 3 | Dec 6 | Dec 11 | Dec 16 | Dec 21 | Dec 30 | Jan 8 |
Freeze probabilities 1991–2020 at Okmulgee Wtr Wks, OK, 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 74437 →Compare Henryetta with another place →
Weather by month in Henryetta
July is the warmest month at Okmulgee Wtr Wks, OK, averaging 93°F by day and 70°F at night; January is the coldest at 50°F and 26°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 71% of years.
Warmth for growing adds up to 4,917 growing degree days a year (base 50°F), fewer than at 82% of the 114 Oklahoma stations. 37% of them (1,838) have built up by the end of June, and July adds the most, 978.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 50 | 26 | 100% | 24 | 16 |
| Feb | 55 | 29 | 100% | 17 | 27 |
| Mar | 64 | 39 | 100% | 9 | 135 |
| Apr | 72 | 47 | 71% | 2 | 306 |
| May | 79 | 57 | 2% | <1 | 557 |
| Jun | 87 | 66 | 0% | 0 | 798 |
| Jul | 93 | 70 | 0% | 0 | 978 |
| Aug | 92 | 68 | 0% | 0 | 928 |
| Sep | 84 | 60 | 1% | 0 | 666 |
| Oct | 75 | 48 | 61% | 2 | 360 |
| Nov | 62 | 37 | 99% | 11 | 122 |
| Dec | 53 | 29 | 100% | 22 | 25 |
Monthly normals 1991–2020 at Okmulgee Wtr Wks, OK (647 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, Okemah, OK, 20 miles west of Henryetta and 288 feet higher, has a last frost 15 days earlier (March 24), a first frost 12 days later (November 9), a season 26 days longer.
When it snows in Henryetta, Oklahoma
Measurable snow is rare here: only 4 of 17 winters from 1991 to 2020 recorded 0.1 inch or more at Dewar 2 NE, OK, 2.5 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 74437
| When | What to do |
|---|---|
| January 28 – February 11 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 11 – February 25 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 11 – March 25 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 8 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 5 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 14 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 28 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 74437 is 13 miles from Okmulgee Wtr Wks, OK, which stands at 647 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station; its figures are presented in full for 74447 (Okmulgee). The 2023 USDA Plant Hardiness Zone Map lists ZIP 74437 in zone 7b, the band where the coldest night of the year averaged 5 to 10°F (-15.0 to -12.2°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.