USDA Hardiness Zone 7b
Frost Dates for 73072 — Norman, Oklahoma
NOAA 1991–2020 normals from Norman 2NW Mesonet, OK (1,181 ft), 2 miles northeast.
Updated
In Norman, the last spring frost (32°F) is around March 31 in half of years and has passed by April 17 in nine years out of ten. The first fall frost comes around November 5, as early as October 21 one year in ten, leaving a typical freeze-free season of 219 days (NOAA, Norman 2NW Mesonet, OK).
- Last spring frost
- March 31
- First fall frost
- November 5
- Growing season
- 219 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 23
- Last snow
- February 13
- Winters with snow
- 96%
- Snow per year
- 4.1"
median, 1991–2020
median, 1991–2020
23 of 24 observed
NOAA normal
Frost risk by date in Norman
Half of springs at Norman 2NW Mesonet, OK see their last 32°F night by March 31; only one in ten is past it by March 12, and one in ten still has one after April 17. Planting tender crops after April 7 leaves a 30% risk of a frost on them, after April 11 20%, and after April 17 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 November 5 in half of years, as early as October 21 one year in ten, and holds off past November 19 one year in ten. A hard freeze of 28°F follows 9 days later, around November 14; in spring the one-in-ten date for 28°F is April 4, 13 days before the 32°F one. The freeze-free season lasts 219 days in a typical year, longer than at 75% of the 114 Oklahoma stations; it reaches 243 days one year in ten and falls short of 197 one year in ten. On average 72 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 12, and return around October 27. Severe cold of 16°F or below comes in 96% of winters, usually between December 25 and February 6.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Mar 27 | Apr 2 | Apr 5 | Apr 8 | Apr 12 | Apr 15 | Apr 19 | Apr 23 | Apr 28 |
| 32°F | Mar 12 | Mar 18 | Mar 23 | Mar 27 | Mar 31 | Apr 4 | Apr 7 | Apr 11 | Apr 17 |
| 28°F | Feb 28 | Mar 4 | Mar 9 | Mar 13 | Mar 16 | Mar 19 | Mar 24 | Mar 30 | Apr 4 |
| 24°F | Feb 15 | Feb 23 | Feb 27 | Mar 2 | Mar 5 | Mar 8 | Mar 11 | Mar 15 | Mar 21 |
| 20°F | Jan 27 | Feb 6 | Feb 13 | Feb 19 | Feb 24 | Feb 27 | Mar 2 | Mar 6 | Mar 12 |
| 16°F96% of yrs | Jan 6 | Jan 18 | Jan 27 | Feb 1 | Feb 6 | Feb 13 | Feb 20 | Feb 26 | Mar 3 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 12 | Oct 18 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 5 | Nov 9 |
| 32°F | Oct 21 | Oct 27 | Oct 31 | Nov 3 | Nov 5 | Nov 8 | Nov 11 | Nov 15 | Nov 19 |
| 28°F | Oct 30 | Nov 4 | Nov 7 | Nov 10 | Nov 14 | Nov 18 | Nov 21 | Nov 25 | Dec 2 |
| 24°F | Nov 5 | Nov 11 | Nov 17 | Nov 21 | Nov 25 | Nov 29 | Dec 2 | Dec 6 | Dec 13 |
| 20°F | Nov 17 | Nov 25 | Nov 30 | Dec 4 | Dec 8 | Dec 14 | Dec 18 | Dec 24 | Jan 1 |
| 16°F96% of yrs | Dec 1 | Dec 9 | Dec 15 | Dec 20 | Dec 25 | Dec 30 | Jan 4 | Jan 12 | Jan 26 |
Freeze probabilities 1991–2020 at Norman 2NW Mesonet, 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 73072 →Compare Norman with another place →
Weather by month in Norman
July is the warmest month at Norman 2NW Mesonet, OK, averaging 93°F by day and 72°F at night; January is the coldest at 51°F and 29°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 50% of years.
Warmth for growing adds up to 5,241 growing degree days a year (base 50°F), more than at 63% of the 114 Oklahoma stations. 38% of them (2,009) have built up by the end of June, and July adds the most, 999.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 51 | 29 | 100% | 21 | 19 |
| Feb | 55 | 32 | 100% | 16 | 57 |
| Mar | 64 | 41 | 95% | 6 | 173 |
| Apr | 72 | 49 | 50% | 2 | 332 |
| May | 79 | 59 | 1% | <1 | 593 |
| Jun | 88 | 68 | 0% | 0 | 837 |
| Jul | 93 | 72 | 0% | 0 | 999 |
| Aug | 93 | 71 | 0% | 0 | 993 |
| Sep | 84 | 63 | 0% | 0 | 702 |
| Oct | 74 | 51 | 33% | 1 | 391 |
| Nov | 62 | 39 | 97% | 8 | 122 |
| Dec | 51 | 31 | 100% | 19 | 25 |
Monthly normals 1991–2020 at Norman 2NW Mesonet, OK (1,181 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, Norman 3SSE, OK, 4 miles southeast of Norman, has a last frost 3 days later (April 3), a first frost 2 days earlier (November 3), a season 7 days shorter.
When it snows in Norman, Oklahoma
The first measurable snow (0.1 inch or more) in Norman usually arrives around December 23, and the last of the season around February 13. Those are the middle dates across the winters of 1991–2020 at Norman 3SSE, OK, 3.5 miles away: half of years saw snow earlier, half later. Snow fell in 96% of those winters. The last 32°F night of spring typically comes 46 days after the last snow.
Planting calendar for 73072
| When | What to do |
|---|---|
| January 20 – February 3 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 3 – February 17 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 3 – March 17 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| March 31 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 13 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 22 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 5 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 73072 is 2 miles from Norman 2NW Mesonet, OK, which stands at 1,181 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 73072 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.