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

Planting zone for Bay Saint Louis, MS

Bay Saint Louis, MS is in USDA zone 9a across its 2 ZIP codes. The median last spring frost is February 21 and the first fall frost December 3.

Bay Saint Louis on the zone map

Outlined: its 1 ZIP code areas · 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
ZIP codes2
Last frostFeb 21
First frostDec 3
Growing season287 days

9a 2 ZIPs

Frost forecast — next 7 nights

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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 Bay Saint Louis, MS

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 21median — 50% chance of a later frost
Safe for tender plantsMarch 18only 10% chance of frost after
First fall frostDecember 3median — 10% chance by Nov 13
Growing season287 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 2 and returns around December 25.

From the NOAA station Waveland, MS, elevation 7 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 Bay Saint Louis

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 10 – Jan 24
SpinachSow outdoors · Jan 10 – Jan 31
Broccoli, cabbageStart indoors · Dec 13 – Dec 27
Broccoli, cabbageTransplant · Jan 31 – Feb 14
Onion setsPlant outdoors · Jan 24 – Feb 7
PotatoesPlant outdoors · Jan 31 – Feb 14
LettuceSow outdoors · Jan 24 – Feb 7
Carrots, beetsSow outdoors · Jan 31 – Feb 14
TomatoesStart indoors · Dec 27 – Jan 10
TomatoesTransplant · Feb 28 – Mar 14
Peppers, eggplantStart indoors · Dec 13 – Dec 27
Peppers, eggplantTransplant · Mar 7 – Mar 21
BeansSow outdoors · Feb 28 – Mar 14
Sweet cornSow outdoors · Feb 28 – Mar 14
Cucumbers, squashSow outdoors · Feb 28 – Mar 14
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 21) 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 39521 came on Jan 11 — 15 days earlier than the 1991–2020 average (Jan 26).

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 Mississippi

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

Trees 80

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °FAtlantic white cedar50 ft · blooms spring · medium shade tolerance · to −36 °F

Shrubs 119

aloe yucca15 ft · blooms early summer · medium shade tolerance · to −1 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican beautyberry6 ft · blooms early summer · medium shade tolerance · to −8 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °F

Wildflowers & perennials 167

American bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °FAmerican spongeplant0.5 ft · blooms mid spring · high shade tolerance · to −24 °FAmerican water horehound1.8 ft · blooms early summer · low shade tolerance · to −38 °F

Grasses 153

American cupscale3 ft · blooms early summer · high shade tolerance · to −18 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbig bluestem6 ft · blooms summer · high shade tolerance · to −46 °Fbig cordgrass8 ft · blooms spring · high shade tolerance · to −3 °Fbighead rush3 ft · blooms early summer · low shade tolerance · to 12 °F

Vines 13

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms spring · low shade tolerance · to −3 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fcupseed30 ft · blooms late spring · low shade tolerance · to −3 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °F

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 Bay Saint Louis, MS.

Soil in Bay Saint Louis, MS

The soil mapped at the center of ZIP 39521 is Saucier — fine sandy loam, moderately well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH5.0strongly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Saucier fine sandy loam, 5 to 8 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 39521; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Bay Saint Louis, MS

Summer high89 °Faverage high, July
Winter low40 °Faverage low, January
Hot days80days a year at 90 °F or more
Freezing nights31nights a year at 32 °F or less
Growing degree days6,027base 50 °F — the season’s usable heat
Longest day14 h 06 mindaylight on June 21
Shortest day10 h 11 mindaylight on December 21
Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb
Precipitation65.9 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 69 °F, low 48 °F 69°48° MarApril: average high 75 °F, low 54 °F 75°54° AprMay: average high 82 °F, low 62 °F 82°62° MayJune: average high 87 °F, low 69 °F 87°69° JunJuly: average high 89 °F, low 71 °F 89°71° JulAugust: average high 89 °F, low 71 °F 89°71° AugSeptember: average high 85 °F, low 67 °F 85°67° SepOctober: average high 78 °F, low 56 °F 78°56° OctNovember: average high 69 °F, low 45 °F 69°45° NovDecember: average high 61 °F, low 41 °F 61°41° Dec

Precipitation by month inches

0″2″4″6″8″January: 4.99 in precipitation 5.0 JanFebruary: 4.20 in precipitation 4.2 FebMarch: 4.84 in precipitation 4.8 MarApril: 6.12 in precipitation 6.1 AprMay: 4.57 in precipitation 4.6 MayJune: 7.01 in precipitation 7.0 JunJuly: 6.96 in precipitation 7.0 JulAugust: 6.83 in precipitation 6.8 AugSeptember: 6.04 in precipitation 6.0 SepOctober: 3.78 in precipitation 3.8 OctNovember: 4.01 in precipitation 4.0 NovDecember: 6.51 in precipitation 6.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Bay St Louis Nasa, MS (6 mi away); precipitation: Stennis-Diamondhead, MS (4 mi away). Daylight is calculated from latitude.

ZIP codes in Bay Saint Louis

395209a
20 to 25 °F
395219a
20 to 25 °F

Mississippi planting zones →

Questions about Bay Saint Louis

What planting zone is Bay Saint Louis, MS?

Bay Saint Louis, MS is in USDA hardiness zone 9a on the 2023 map (9a: 20 to 25 °F).

When is the last frost in Bay Saint Louis, MS?

The median last spring frost is February 21 and the median first fall frost is December 3 (NOAA 1991–2020 normals, Waveland station).

When can I plant a garden in Bay Saint Louis, MS?

Cool-season crops like peas and spinach go in around Jan 10 – Jan 31; tomatoes, peppers, beans and squash after about Feb 28, once frost risk has passed.

What kind of onions grow in Bay Saint Louis, MS?

Short-day onions: the longest day is 14 h 06 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

How much rain and snow does Bay Saint Louis, MS get?

About 65.9 inches of precipitation a year (NOAA 1991–2020 normals).