USDA Hardiness Zone 8b
Frost Dates for 39150 — Port Gibson, Mississippi
NOAA 1991–2020 normals from Port Gibson 1 NE, MS (120 ft), 1 miles northeast.
Updated
In Port Gibson, the last spring frost (32°F) is around March 17 in half of years and has passed by April 7 in nine years out of ten. The first fall frost comes around November 12, as early as October 29 one year in ten, leaving a typical freeze-free season of 241 days (NOAA, Port Gibson 1 NE, MS).
- Last spring frost
- March 17
- First fall frost
- November 12
- Growing season
- 241 days
- Hardiness zone
- 8b
50% probability
50% probability
freeze-free, 50%
15 to 20°F (-9.4 to -6.7°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 19%
- Snow per year
- 0.5"
median, 1991–2020
median, 1991–2020
5 of 26 observed
NOAA normal
Frost risk by date in Port Gibson
Half of springs at Port Gibson 1 NE, MS see their last 32°F night by March 17; only one in ten is past it by February 24, and one in ten still has one after April 7. Planting tender crops after March 27 leaves a 30% risk of a frost on them, after April 1 20%, and after April 7 10%. The 21 days between the even-odds date and the one-in-ten date is wider than at 73% of the 96 Mississippi 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 November 12 in half of years, as early as October 29 one year in ten, and holds off past December 1 one year in ten. A hard freeze of 28°F follows 13 days later, around November 25; in spring the one-in-ten date for 28°F is March 22, 16 days before the 32°F one. The freeze-free season lasts 241 days in a typical year, longer than at 52% of the 96 Mississippi stations; it reaches 271 days one year in ten and falls short of 213 one year in ten. On average 49 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 March 31, and return around November 2. Nights of 24°F, cold enough to damage hardier plants, come in 97% of winters and 16°F in 36%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Mar 12 | Mar 19 | Mar 25 | Mar 28 | Mar 31 | Apr 4 | Apr 7 | Apr 12 | Apr 19 |
| 32°F | Feb 24 | Mar 2 | Mar 7 | Mar 12 | Mar 17 | Mar 21 | Mar 27 | Apr 1 | Apr 7 |
| 28°F | Feb 3 | Feb 15 | Feb 21 | Feb 26 | Mar 1 | Mar 5 | Mar 9 | Mar 14 | Mar 22 |
| 24°F97% of yrs | Jan 15 | Jan 29 | Feb 3 | Feb 10 | Feb 15 | Feb 22 | Feb 27 | Mar 4 | Mar 11 |
| 20°F75% of yrs | Dec 30 | Jan 9 | Jan 18 | Jan 27 | Jan 31 | Feb 4 | Feb 10 | Feb 20 | Mar 1 |
| 16°F36% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 20 | Oct 24 | Oct 28 | Oct 31 | Nov 2 | Nov 4 | Nov 7 | Nov 11 | Nov 17 |
| 32°F | Oct 29 | Nov 2 | Nov 5 | Nov 8 | Nov 12 | Nov 15 | Nov 20 | Nov 24 | Dec 1 |
| 28°F | Nov 5 | Nov 11 | Nov 16 | Nov 21 | Nov 25 | Nov 30 | Dec 5 | Dec 10 | Dec 27 |
| 24°F97% of yrs | Nov 15 | Nov 24 | Dec 1 | Dec 6 | Dec 13 | Dec 25 | Jan 1 | Jan 6 | Jan 18 |
| 20°F75% of yrs | Dec 4 | Dec 12 | Dec 25 | Jan 1 | Jan 4 | Jan 9 | Jan 15 | Jan 25 | Feb 5 |
| 16°F36% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Port Gibson 1 NE, MS, 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 39150 →Compare Port Gibson with another place →
Weather by month in Port Gibson
July is the warmest month at Port Gibson 1 NE, MS, averaging 93°F by day and 72°F at night; January is the coldest at 60°F and 36°F. A freezing night is all but certain in every month from December to February (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 77% of years and April still brings one in 22% of years.
Warmth for growing adds up to 6,266 growing degree days a year (base 50°F), more than at 76% of the 96 Mississippi stations. 41% of them (2,587) have built up by the end of June, and July adds the most, 1,003. Precipitation totals 56.4 inches a year, most in January (6.1") and least in August (3.6"); May to September bring 35% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 60 | 36 | 6.1 | 99% | 15 | 95 |
| Feb | 64 | 38 | 5.1 | 98% | 10 | 125 |
| Mar | 71 | 46 | 6.0 | 77% | 4 | 294 |
| Apr | 78 | 53 | 5.5 | 22% | <1 | 459 |
| May | 85 | 62 | 4.5 | 0% | 0 | 719 |
| Jun | 91 | 69 | 4.1 | 0% | 0 | 894 |
| Jul | 93 | 72 | 3.9 | 0% | 0 | 1003 |
| Aug | 93 | 71 | 3.6 | 0% | 0 | 997 |
| Sep | 89 | 65 | 3.8 | 0% | 0 | 816 |
| Oct | 80 | 53 | 4.1 | 14% | 1 | 518 |
| Nov | 69 | 43 | 4.4 | 88% | 6 | 223 |
| Dec | 62 | 38 | 5.3 | 98% | 13 | 122 |
Monthly normals 1991–2020 at Port Gibson 1 NE, MS (120 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, St Joseph 3 N, LA, 15 miles west of Port Gibson, has a last frost 4 days earlier (March 13), a first frost 2 days earlier (November 10), a season 1 day longer.
When it snows in Port Gibson, Mississippi
Measurable snow is rare here: only 5 of 26 winters from 1991 to 2020 recorded 0.1 inch or more at Port Gibson 1 NE, MS, 1.1 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 39150
| When | What to do |
|---|---|
| January 6 – January 20 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| January 20 – February 3 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| February 17 – March 3 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| March 17 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 20 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 29 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 12 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 39150 is 1 mile from Port Gibson 1 NE, MS, which stands at 120 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 39150 in zone 8b, the band where the coldest night of the year averaged 15 to 20°F (-9.4 to -6.7°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across Mississippi →
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.