Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 29940 — Seabrook, SC

ZIP code 29940 (Seabrook, Beaufort County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 28 and the first fall frost December 3.

Where ZIP 29940 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone9a20 to 25 °F
Coldest night−6.7 to −3.9 °C
Last frostFeb 28
First frostDec 3
2012 zone8b

Was 8b on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Seabrook, SC…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Seabrook, SC

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 28median — 50% chance of a later frost
Safe for tender plantsMarch 21only 10% chance of frost after
First fall frostDecember 3median — 10% chance by Nov 14
Growing season279 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 8 and returns around December 27.

From the NOAA station Beaufort Mcas, SC — 6 miles away, elevation 36 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 29940

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 17 – Jan 31
SpinachSow outdoors · Jan 17 – Feb 7
Broccoli, cabbageStart indoors · Dec 20 – Jan 3
Broccoli, cabbageTransplant · Feb 7 – Feb 21
Onion setsPlant outdoors · Jan 31 – Feb 14
PotatoesPlant outdoors · Feb 7 – Feb 21
LettuceSow outdoors · Jan 31 – Feb 14
Carrots, beetsSow outdoors · Feb 7 – Feb 21
TomatoesStart indoors · Jan 3 – Jan 17
TomatoesTransplant · Mar 7 – Mar 21
Peppers, eggplantStart indoors · Dec 20 – Jan 3
Peppers, eggplantTransplant · Mar 14 – Mar 28
BeansSow outdoors · Mar 7 – Mar 21
Sweet cornSow outdoors · Mar 7 – Mar 21
Cucumbers, squashSow outdoors · Mar 7 – Mar 21
Fall lettuce, spinachSow outdoors · Oct 8 – Oct 22
GarlicPlant cloves · Nov 19 – Dec 24
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 28) and first fall frost (Dec 3) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 29940 came on Feb 1 — about the same time as the 1991–2020 average (Jan 30).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Soil in Seabrook, SC

The soil mapped at the center of ZIP 29940 is Chisolm — loamy fine sand, somewhat excessively drained.

TextureLoamy fine sanddrains and warms fast; dries out and needs more feeding
pH5.3strongly acidic; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter0.75%low — add compost
Hydrologic groupBwater soaks in moderately
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Chisolm loamy fine sand, 0 to 6 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 29940; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Seabrook, SC

Summer high92 °Faverage high, July
Winter low40 °Faverage low, January
Hot days73days a year at 90 °F or more
Freezing nights17nights a year at 32 °F or less
Growing degree days6,582base 50 °F — the season’s usable heat
Longest day14 h 18 mindaylight on June 21
Shortest day10 h 00 mindaylight on December 21
Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb
Precipitation45 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°32 °FJanuary: average high 60 °F, low 40 °F 60°40° JanFebruary: average high 64 °F, low 43 °F 64°43° FebMarch: average high 70 °F, low 49 °F 70°49° MarApril: average high 77 °F, low 56 °F 77°56° AprMay: average high 84 °F, low 64 °F 84°64° MayJune: average high 89 °F, low 71 °F 89°71° JunJuly: average high 92 °F, low 75 °F 92°75° JulAugust: average high 90 °F, low 74 °F 90°74° AugSeptember: average high 86 °F, low 70 °F 86°70° SepOctober: average high 78 °F, low 59 °F 78°59° OctNovember: average high 69 °F, low 48 °F 69°48° NovDecember: average high 63 °F, low 43 °F 63°43° Dec

Precipitation by month inches

0″2″4″6″January: 2.90 in precipitation 2.9 JanFebruary: 2.91 in precipitation 2.9 FebMarch: 3.11 in precipitation 3.1 MarApril: 3.06 in precipitation 3.1 AprMay: 2.50 in precipitation 2.5 MayJune: 4.99 in precipitation 5.0 JunJuly: 5.57 in precipitation 5.6 JulAugust: 6.50 in precipitation 6.5 AugSeptember: 4.03 in precipitation 4.0 SepOctober: 3.77 in precipitation 3.8 OctNovember: 2.51 in precipitation 2.5 NovDecember: 3.17 in precipitation 3.2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Beaufort Mcas, SC (6 mi away); precipitation: Beaufort Mcas, SC (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9a.

299149a
Dale, SC · <1 mi
299319a
Lobeco, SC · 4 mi
299049a
Beaufort, SC · 6 mi
299079a
Beaufort, SC · 7 mi
299039a
Beaufort, SC · 8 mi
299419a
Sheldon, SC · 8 mi
299069a
Beaufort, SC · 9 mi
294469a
Green Pond, SC · 10 mi

South Carolina planting zones →

Questions about 29940

What planting zone is ZIP code 29940?

ZIP code 29940 (Seabrook, SC) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Seabrook, SC?

The median last spring frost (32 °F) near 29940 is February 28; after March 21 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Beaufort Mcas station.

When is the first frost in Seabrook, SC?

The median first fall frost near 29940 is December 3, giving a median frost-free growing season of 279 days.

When should I plant tomatoes in 29940?

Start tomato seeds indoors around Jan 3 – Jan 17 and set transplants outside around Mar 7 – Mar 21, one to three weeks after the median last frost.

How much rain and snow does 29940 get?

About 45 inches of precipitation a year (NOAA 1991–2020 normals, Beaufort Mcas station).

How hot do summers get in Seabrook, SC?

The average high peaks at 92 °F in July, with about 73 days a year at 90 °F or more.

What kind of soil does 29940 have?

The USDA soil survey maps Chisolm at the center of ZIP 29940: loamy fine sand, somewhat excessively drained, pH about 5.3 (strongly acidic).

Did spring come early in Seabrook, SC in 2026?

Spring leaf-out near 29940 came on Feb 1 in 2026, about the same as the 1991–2020 average (Jan 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Seabrook, SC?

Short-day onions: the longest day near 29940 is 14 h 18 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

Did the zone for 29940 change?

Yes. The 2012 USDA map put 29940 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.