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

Planting zone for 21821 — Deal Island, MD

ZIP code 21821 (Deal Island, Somerset County) is in USDA zone 8a: the coldest winter night averages 10 to 15 °F. The median last spring frost is April 3 and the first fall frost November 7.

Where ZIP 21821 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.

Zone8a10 to 15 °F
Coldest night−12.2 to −9.4 °C
Last frostApr 3
First frostNov 7
2012 zone7b

Was 7b 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 8a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Deal Island, MD…

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 Deal Island, MD

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 3median — 50% chance of a later frost
Safe for tender plantsApril 25only 10% chance of frost after
First fall frostNovember 7median — 10% chance by Oct 27
Growing season217 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 21 and returns around November 21.

From the NOAA station Salisbury, MD — 22 miles away, elevation 10 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 21821

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 20 – Mar 6
SpinachSow outdoors · Feb 20 – Mar 13
Broccoli, cabbageStart indoors · Jan 23 – Feb 6
Broccoli, cabbageTransplant · Mar 13 – Mar 27
Onion setsPlant outdoors · Mar 6 – Mar 20
PotatoesPlant outdoors · Mar 13 – Mar 27
LettuceSow outdoors · Mar 6 – Mar 20
Carrots, beetsSow outdoors · Mar 13 – Mar 27
TomatoesStart indoors · Feb 6 – Feb 20
TomatoesTransplant · Apr 10 – Apr 24
Peppers, eggplantStart indoors · Jan 23 – Feb 6
Peppers, eggplantTransplant · Apr 17 – May 1
BeansSow outdoors · Apr 10 – Apr 24
Sweet cornSow outdoors · Apr 10 – Apr 24
Cucumbers, squashSow outdoors · Apr 10 – Apr 24
Fall lettuce, spinachSow outdoors · Sep 12 – Sep 26
GarlicPlant cloves · Oct 24 – Nov 28
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 3) and first fall frost (Nov 7) 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 21821 came on Mar 10 — 5 days later than the 1991–2020 average (Mar 5).

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 8a in Maryland

629 plants native to the lower 48 states, recorded in Maryland, and rated by the USDA to survive 10 °F or colder — the bottom of zone 8a. Each links to its USDA PLANTS profile.

Trees 84

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 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 129

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican beautyberry6 ft · blooms early summer · medium shade tolerance · to −8 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °F

Wildflowers & perennials 209

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 speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °FAmerican spongeplant0.5 ft · blooms mid spring · high shade tolerance · to −24 °F

Grasses 181

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °FAmerican cupscale3 ft · blooms early summer · high shade tolerance · to −18 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °FAtlantic mannagrass3 ft · blooms summer · low shade tolerance · to −8 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °F

Vines 12

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms 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 °Fgraybark grape50 ft · blooms late spring · medium shade tolerance · to −8 °Fheartleaf peppervine2 ft · blooms late spring · low shade tolerance · to −8 °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 Deal Island, MD.

Soil in Deal Island, MD

The soil mapped at the center of ZIP 21821 is Tangier — mucky peat, very poorly drained.

TextureMucky peattop layer
pH5.6moderately acidic; most vegetables like 6.0–7.0
DrainageVery poorly drainedconsider raised beds
Organic matter70.32%high
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Tangier mucky peat, 0 to 2 percent slopes, very frequently flooded, tidal.

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 21821; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Deal Island, MD

Summer high89 °Faverage high, July
Winter low29 °Faverage low, January
Hot days31days a year at 90 °F or more
Freezing nights71nights a year at 32 °F or less
Growing degree days4,456base 50 °F — the season’s usable heat
Longest day14 h 49 mindaylight on June 21
Shortest day9 h 30 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation47.2 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 47 °F, low 29 °F 47°29° JanFebruary: average high 50 °F, low 30 °F 50°30° FebMarch: average high 58 °F, low 37 °F 58°37° MarApril: average high 69 °F, low 46 °F 69°46° AprMay: average high 77 °F, low 55 °F 77°55° MayJune: average high 85 °F, low 65 °F 85°65° JunJuly: average high 89 °F, low 70 °F 89°70° JulAugust: average high 86 °F, low 68 °F 86°68° AugSeptember: average high 81 °F, low 62 °F 81°62° SepOctober: average high 71 °F, low 50 °F 71°50° OctNovember: average high 60 °F, low 40 °F 60°40° NovDecember: average high 52 °F, low 33 °F 52°33° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.27 in precipitation 3.3 JanFebruary: 2.89 in precipitation 2.9 FebMarch: 4.07 in precipitation 4.1 MarApril: 3.78 in precipitation 3.8 AprMay: 4.04 in precipitation 4.0 MayJune: 4.13 in precipitation 4.1 JunJuly: 4.41 in precipitation 4.4 JulAugust: 4.57 in precipitation 4.6 AugSeptember: 4.41 in precipitation 4.4 SepOctober: 4.46 in precipitation 4.5 OctNovember: 3.30 in precipitation 3.3 NovDecember: 3.87 in precipitation 3.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Salisbury, MD (22 mi away); precipitation: Princess Anne 4.4 Wsw, MD (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

3 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

218408a
Nanticoke, MD · 6 mi
218678a
Upper Fairmount, MD · 8 mi
216278a
Crocheron, MD · 8 mi
218148a
Bivalve, MD · 9 mi
218367b
Manokin, MD · 9 mi
218657b
Tyaskin, MD · 10 mi
218717b
Westover, MD · 10 mi
216728a
Toddville, MD · 10 mi

Maryland planting zones →

Questions about 21821

What planting zone is ZIP code 21821?

ZIP code 21821 (Deal Island, MD) is in USDA hardiness zone 8a on the 2023 map: the coldest night of an average winter reaches 10 to 15 °F (−12.2 to −9.4 °C).

When is the last frost in Deal Island, MD?

The median last spring frost (32 °F) near 21821 is April 3; after April 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Salisbury station.

When is the first frost in Deal Island, MD?

The median first fall frost near 21821 is November 7, giving a median frost-free growing season of 217 days.

When should I plant tomatoes in 21821?

Start tomato seeds indoors around Feb 6 – Feb 20 and set transplants outside around Apr 10 – Apr 24, one to three weeks after the median last frost.

How much rain and snow does 21821 get?

About 47.2 inches of precipitation a year (NOAA 1991–2020 normals, Princess Anne 4.4 Wsw station).

How hot do summers get in Deal Island, MD?

The average high peaks at 89 °F in July, with about 31 days a year at 90 °F or more.

What kind of soil does 21821 have?

The USDA soil survey maps Tangier at the center of ZIP 21821: mucky peat, very poorly drained, pH about 5.6 (moderately acidic).

Did spring come early in Deal Island, MD in 2026?

Spring leaf-out near 21821 came on Mar 10 in 2026, 5 days later than the 1991–2020 average (Mar 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Deal Island, MD?

Intermediate onions: the longest day near 21821 is 14 h 49 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 21821 change?

Yes. The 2012 USDA map put 21821 in zone 7b; the 2023 map puts it in zone 8a. The newer map uses 1991–2020 data and more weather stations.