Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 31522 — Saint Simons Island, GA

ZIP code 31522 (Saint Simons Island, Glynn County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 9 and the first fall frost December 26.

Where ZIP 31522 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 9

First frostDec 26

2012 zone9a

Same zone as on the 2012 map. 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 Saint Simons Island, GA…

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 Saint Simons Island, GA

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostFebruary 9median — 50% chance of a later frost

Safe for tender plantsMarch 6only 10% chance of frost after

First fall frostDecember 26median — 10% chance by Nov 30

Growing season312 daysfrost-free, median

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

From the NOAA station Brunswick Malcolm Mckinnon Airport, GA — 8 miles away, elevation 16 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 31522

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Dec 29 – Jan 12

SpinachSow outdoors · Dec 29 – Jan 19

Broccoli, cabbageStart indoors · Dec 1 – Dec 15

Broccoli, cabbageTransplant · Jan 19 – Feb 2

Onion setsPlant outdoors · Jan 12 – Jan 26

PotatoesPlant outdoors · Jan 19 – Feb 2

LettuceSow outdoors · Jan 12 – Jan 26

Carrots, beetsSow outdoors · Jan 19 – Feb 2

TomatoesStart indoors · Dec 15 – Dec 29

TomatoesTransplant · Feb 16 – Mar 2

Peppers, eggplantStart indoors · Dec 1 – Dec 15

Peppers, eggplantTransplant · Feb 23 – Mar 9

BeansSow outdoors · Feb 16 – Mar 2

Sweet cornSow outdoors · Feb 16 – Mar 2

Cucumbers, squashSow outdoors · Feb 16 – Mar 2

Fall lettuce, spinachSow outdoors · Oct 31 – Nov 14

GarlicPlant cloves · Dec 12 – Jan 16

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 9) and first fall frost (Dec 26) 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 31522 came on Jan 28 — about the same time as the 1991–2020 average (Jan 26).

average
Jan 262026
Jan 28

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).

Native plants for zone 9a in Georgia

603 plants native to the lower 48 states, recorded in Georgia, and rated by the USDA to survive 20 °F or colder — the bottom of zone 9a. Each links to its USDA PLANTS profile.

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Saint Simons Island, GA.

Soil in Saint Simons Island, GA

The soil mapped at the center of ZIP 31522 is Mandarin — fine sand, somewhat poorly drained.

TextureFine sanddrains and warms fast; dries out and needs more feeding

pH4.2strongly acidic; most vegetables like 6.0–7.0

DrainageSomewhat poorly drainedconsider raised beds

Organic matter1.25%low — add compost

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Mandarin fine sand, 0 to 2 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 31522; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Saint Simons Island, GA

Summer high91 °Faverage high, July

Winter low44 °Faverage low, January

Hot days47days a year at 90 °F or more

Freezing nights8nights a year at 32 °F or less

Growing degree days7,170base 50 °F — the season’s usable heat

Longest day14 h 11 mindaylight on June 21

Shortest day10 h 07 mindaylight on December 21

Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb

Precipitation45.4 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Brunswick Malcolm Mckinnon Airport, GA (8 mi away); precipitation: Brunswick Malcolm Mckinnon Airport, GA (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9a.

315619a

Sea Island, GA · 4 mi

Brunswick, GA · 10 mi

315219a

Brunswick, GA · 12 mi

315259a

Brunswick, GA · 12 mi

313279a

Sapelo Island, GA · 12 mi

315279a

Jekyll Island, GA · 13 mi

Georgia planting zones →

Questions about 31522

What planting zone is ZIP code 31522?

ZIP code 31522 (Saint Simons Island, GA) 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 Saint Simons Island, GA?

The median last spring frost (32 °F) near 31522 is February 9; after March 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Brunswick Malcolm Mckinnon Airport station.

When is the first frost in Saint Simons Island, GA?

The median first fall frost near 31522 is December 26, giving a median frost-free growing season of 312 days.

When should I plant tomatoes in 31522?

Start tomato seeds indoors around Dec 15 – Dec 29 and set transplants outside around Feb 16 – Mar 2, one to three weeks after the median last frost.

How much rain and snow does 31522 get?

About 45.4 inches of precipitation a year (NOAA 1991–2020 normals, Brunswick Malcolm Mckinnon Airport station).

How hot do summers get in Saint Simons Island, GA?

The average high peaks at 91 °F in July, with about 47 days a year at 90 °F or more.

What kind of soil does 31522 have?

The USDA soil survey maps Mandarin at the center of ZIP 31522: fine sand, somewhat poorly drained, pH about 4.2 (strongly acidic).

Did spring come early in Saint Simons Island, GA in 2026?

Spring leaf-out near 31522 came on Jan 28 in 2026, about the same as the 1991–2020 average (Jan 26), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Saint Simons Island, GA?

Short-day onions: the longest day near 31522 is 14 h 11 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.