USDA Hardiness Zone 8a
Frost Dates for 72921 — Alma, Arkansas
NOAA 1991–2020 normals from Mountainburg 2 NE, AR (793 ft), 12 miles north.
Updated
In Alma, the last spring frost (32°F) is around April 9 in half of years and has passed by April 28 in nine years out of ten. The first fall frost comes around October 28, as early as October 14 one year in ten, leaving a typical freeze-free season of 201 days (NOAA, Mountainburg 2 NE, AR).
- Last spring frost
- April 9
- First fall frost
- October 28
- Growing season
- 201 days
- Hardiness zone
- 8a
50% probability
50% probability
freeze-free, 50%
10 to 15°F (-12.2 to -9.4°C) coldest night
- First snow
- December 24
- Last snow
- January 29
- Winters with snow
- 75%
- Snow per year
- 3.1"
median, 1991–2020
median, 1991–2020
15 of 20 observed
NOAA normal
Frost risk by date in Alma
Half of springs at Mountainburg 2 NE, AR see their last 32°F night by April 9; only one in ten is past it by March 24, and one in ten still has one after April 28. Planting tender crops after April 16 leaves a 30% risk of a frost on them, after April 21 20%, and after April 28 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 80% of the 105 Arkansas 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 14 one year in ten, and holds off past November 12 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 14, 14 days before the 32°F one. The freeze-free season lasts 201 days in a typical year, shorter than at 90% of the 105 Arkansas stations; it reaches 225 days one year in ten and falls short of 177 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 14 days longer, to about April 23, and return around October 18. Severe cold of 16°F or below comes in 99% of winters, usually between December 19 and February 16.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 7 | Apr 12 | Apr 15 | Apr 19 | Apr 23 | Apr 26 | Apr 30 | May 3 | May 8 |
| 32°F | Mar 24 | Mar 30 | Apr 3 | Apr 6 | Apr 9 | Apr 13 | Apr 16 | Apr 21 | Apr 28 |
| 28°F | Mar 8 | Mar 14 | Mar 20 | Mar 24 | Mar 28 | Mar 31 | Apr 3 | Apr 7 | Apr 14 |
| 24°F | Feb 24 | Mar 1 | Mar 6 | Mar 11 | Mar 15 | Mar 19 | Mar 24 | Mar 29 | Apr 4 |
| 20°F | Feb 5 | Feb 15 | Feb 22 | Feb 27 | Mar 2 | Mar 6 | Mar 11 | Mar 16 | Mar 23 |
| 16°F99% of yrs | Jan 19 | Jan 30 | Feb 3 | Feb 10 | Feb 16 | Feb 23 | Feb 28 | Mar 4 | Mar 10 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 5 | Oct 9 | Oct 13 | Oct 16 | Oct 18 | Oct 21 | Oct 24 | Oct 27 | Nov 2 |
| 32°F | Oct 14 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 2 | Nov 6 | Nov 12 |
| 28°F | Oct 23 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 10 | Nov 14 | Nov 19 | Nov 25 |
| 24°F | Nov 1 | Nov 5 | Nov 10 | Nov 13 | Nov 18 | Nov 21 | Nov 27 | Dec 1 | Dec 6 |
| 20°F | Nov 10 | Nov 17 | Nov 22 | Nov 27 | Dec 1 | Dec 5 | Dec 9 | Dec 15 | Dec 23 |
| 16°F99% of yrs | Nov 21 | Dec 1 | Dec 6 | Dec 12 | Dec 19 | Dec 25 | Dec 31 | Jan 6 | Jan 15 |
Freeze probabilities 1991–2020 at Mountainburg 2 NE, AR, 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 72921 →Compare Alma with another place →
Frost risk through the year in Alma
In Alma, the spring curve drops under 10% on April 28 and the fall curve passes 10% on October 14, 169 days later; that gap is shorter than at 91% of the 105 Arkansas stations with frost dates. The spring risk falls from 90% to 10% over 35 days (March 24 to April 28) and the fall risk climbs from 10% to 90% over 29 days (October 14 to November 12): both ends of the season vary about as much. At Fort Smith Regional Airport, AR, 14 miles southwest, the same gap runs from April 11 to October 23, 26 days longer.
| Planted on | Another 32°F night | 28°F night |
|---|---|---|
| Mar 26 | 87% | 55% |
| Apr 2 | 73% | 33% |
| Apr 950% date | 50% | 17% |
| Apr 16 | 30% | under 10% |
| Apr 23 | 17% | under 10% |
| Apr 30 | under 10% | under 10% |
Weather by month in Alma
July is the warmest month at Mountainburg 2 NE, AR, averaging 92°F by day and 67°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 74% of years.
Warmth for growing adds up to 4,592 growing degree days a year (base 50°F), fewer than at 76% of the 105 Arkansas stations. 37% of them (1,711) have built up by the end of June, and July adds the most, 914. Precipitation totals 53.6 inches a year, most in May (6.3") and least in February (3.1"); May to September bring 45% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 49 | 26 | 3.3 | 100% | 23 | 13 |
| Feb | 54 | 29 | 3.1 | 100% | 18 | 29 |
| Mar | 63 | 37 | 4.5 | 99% | 10 | 109 |
| Apr | 72 | 46 | 5.3 | 74% | 2 | 277 |
| May | 79 | 55 | 6.3 | 5% | 0 | 523 |
| Jun | 87 | 64 | 4.5 | 0% | 0 | 760 |
| Jul | 92 | 67 | 4.1 | 0% | 0 | 914 |
| Aug | 91 | 66 | 4.1 | 0% | 0 | 882 |
| Sep | 84 | 58 | 5.1 | 0% | 0 | 639 |
| Oct | 74 | 47 | 4.9 | 62% | 2 | 335 |
| Nov | 61 | 36 | 4.7 | 99% | 11 | 91 |
| Dec | 52 | 29 | 3.7 | 100% | 21 | 21 |
Monthly normals 1991–2020 at Mountainburg 2 NE, AR (793 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, Fort Smith Regional Airport, AR, 14 miles southwest of Alma and 344 feet lower, has a last frost 15 days earlier (March 25), a first frost 9 days later (November 6), a season 23 days longer.
When it snows in Alma, Arkansas
The first measurable snow (0.1 inch or more) in Alma usually arrives around December 24, and the last of the season around January 29. Those are the middle dates across the winters of 1991–2020 at Mountainburg 2 NE, AR, 11.5 miles away: half of years saw snow earlier, half later. Snow fell in 75% of those winters. The last 32°F night of spring typically comes 70 days after the last snow.
Planting calendar for 72921
| When | What to do |
|---|---|
| January 29 – February 12 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 12 – February 26 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 12 – March 26 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 9 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 72921 is 12 miles from Mountainburg 2 NE, AR, which stands at 793 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 72921 in zone 8a, the band where the coldest night of the year averaged 10 to 15°F (-12.2 to -9.4°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.