USDA Hardiness Zone 7b
Frost Dates for 74133 — Tulsa, Oklahoma
NOAA 1991–2020 normals from Bixby, OK (605 ft), 4 miles south.
Updated
In Tulsa, the last spring frost (32°F) is around April 1 in half of years and has passed by April 20 in nine years out of ten. The first fall frost comes around November 1, as early as October 16 one year in ten, leaving a typical freeze-free season of 212 days (NOAA, Bixby, OK).
- Last spring frost
- April 1
- First fall frost
- November 1
- Growing season
- 212 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
- December 10
- Last snow
- February 27
- Winters with snow
- 100%
- Snow per year
- 8.7"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Tulsa
Half of springs at Bixby, OK see their last 32°F night by April 1; only one in ten is past it by March 12, and one in ten still has one after April 20. Planting tender crops after April 8 leaves a 30% risk of a frost on them, after April 12 20%, and after April 20 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 81% of the 114 Oklahoma stations behind this site's ZIP pages.
In fall the first 32°F night comes by November 1 in half of years, as early as October 16 one year in ten, and holds off past November 13 one year in ten. A hard freeze of 28°F follows 8 days later, around November 9; in spring the one-in-ten date for 28°F is April 7, 13 days before the 32°F one. The freeze-free season lasts 212 days in a typical year, longer than at 54% of the 114 Oklahoma stations; it reaches 237 days one year in ten and falls short of 190 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 12 days longer, to about April 13, and return around October 22. Severe cold of 16°F or below comes in 99% of winters, usually between December 18 and February 14.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Mar 27 | Mar 31 | Apr 5 | Apr 9 | Apr 13 | Apr 16 | Apr 21 | Apr 25 | Apr 29 |
| 32°F | Mar 12 | Mar 20 | Mar 24 | Mar 28 | Apr 1 | Apr 4 | Apr 8 | Apr 12 | Apr 20 |
| 28°F | Feb 28 | Mar 5 | Mar 10 | Mar 14 | Mar 17 | Mar 22 | Mar 27 | Mar 31 | Apr 7 |
| 24°F | Feb 17 | Feb 23 | Feb 28 | Mar 3 | Mar 6 | Mar 10 | Mar 13 | Mar 17 | Mar 25 |
| 20°F | Feb 2 | Feb 11 | Feb 17 | Feb 21 | Feb 26 | Mar 1 | Mar 4 | Mar 8 | Mar 13 |
| 16°F99% of yrs | Jan 17 | Jan 28 | Feb 2 | Feb 8 | Feb 14 | Feb 19 | Feb 25 | Mar 1 | Mar 8 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 8 | Oct 12 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 4 |
| 32°F | Oct 16 | Oct 22 | Oct 26 | Oct 29 | Nov 1 | Nov 2 | Nov 5 | Nov 9 | Nov 13 |
| 28°F | Oct 26 | Oct 31 | Nov 3 | Nov 5 | Nov 9 | Nov 12 | Nov 16 | Nov 21 | Nov 27 |
| 24°F | Nov 2 | Nov 8 | Nov 12 | Nov 16 | Nov 20 | Nov 24 | Nov 29 | Dec 1 | Dec 7 |
| 20°F | Nov 13 | Nov 20 | Nov 24 | Nov 28 | Dec 1 | Dec 5 | Dec 9 | Dec 15 | Dec 23 |
| 16°F99% of yrs | Nov 25 | Nov 30 | Dec 6 | Dec 12 | Dec 18 | Dec 23 | Dec 29 | Jan 4 | Jan 12 |
Freeze probabilities 1991–2020 at Bixby, 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 74133 →Compare Tulsa with another place →
Weather by month in Tulsa
July is the warmest month at Bixby, OK, averaging 94°F by day and 71°F at night; January is the coldest at 49°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 51% of years.
Warmth for growing adds up to 4,983 growing degree days a year (base 50°F), fewer than at 74% of the 114 Oklahoma stations. 38% of them (1,874) have built up by the end of June, and July adds the most, 992.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 49 | 26 | 100% | 24 | 13 |
| Feb | 54 | 29 | 100% | 18 | 26 |
| Mar | 63 | 38 | 97% | 10 | 135 |
| Apr | 72 | 47 | 51% | 1 | 303 |
| May | 80 | 57 | 0% | 0 | 572 |
| Jun | 88 | 67 | 0% | 0 | 825 |
| Jul | 94 | 71 | 0% | 0 | 992 |
| Aug | 93 | 69 | 0% | 0 | 953 |
| Sep | 85 | 60 | 0% | 0 | 680 |
| Oct | 74 | 48 | 50% | 1 | 357 |
| Nov | 62 | 36 | 100% | 12 | 105 |
| Dec | 52 | 29 | 100% | 21 | 22 |
Monthly normals 1991–2020 at Bixby, OK (605 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, Tulsa R L Jones Jr Airport, OK, 6 miles west of Tulsa, has a last frost 2 days earlier (March 30), a first frost 3 days later (November 4), a season 8 days longer.
When it snows in Tulsa, Oklahoma
The first measurable snow (0.1 inch or more) in Tulsa usually arrives around December 10, and the last of the season around February 27. Those are the middle dates across the winters of 1991–2020 at Tulsa International Airport, OK, 10.8 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 33 days after the last snow.
Planting calendar for 74133
| When | What to do |
|---|---|
| January 21 – February 4 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 4 – February 18 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 4 – March 18 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 1 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 9 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 18 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 1 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 74133 is 4 miles from Bixby, OK, which stands at 605 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station; its figures are presented in full for 74012 (Broken Arrow). The 2023 USDA Plant Hardiness Zone Map lists ZIP 74133 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.