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

Planting zone for 02638 — Dennis, MA

ZIP code 02638 (Dennis, Barnstable County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 22 and the first fall frost October 28.

Where ZIP 02638 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.

Zone7b5 to 10 °F

Coldest night−15 to −12.2 °C

Last frostApr 22

First frostOct 28

2012 zone7a

Was 7a 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 7b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Dennis, MA…

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 Dennis, MA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 22median — 50% chance of a later frost

Safe for tender plantsMay 5only 10% chance of frost after

First fall frostOctober 28median — 10% chance by Oct 13

Growing season188 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 7 and returns around November 9.

From the NOAA station Hyannis Barnstable Municipal Airport, MA — 6 miles away, elevation 56 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 02638

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 11 – Mar 25

SpinachSow outdoors · Mar 11 – Apr 1

Broccoli, cabbageStart indoors · Feb 11 – Feb 25

Broccoli, cabbageTransplant · Apr 1 – Apr 15

Onion setsPlant outdoors · Mar 25 – Apr 8

PotatoesPlant outdoors · Apr 1 – Apr 15

LettuceSow outdoors · Mar 25 – Apr 8

Carrots, beetsSow outdoors · Apr 1 – Apr 15

TomatoesStart indoors · Feb 25 – Mar 11

TomatoesTransplant · Apr 29 – May 13

Peppers, eggplantStart indoors · Feb 11 – Feb 25

Peppers, eggplantTransplant · May 6 – May 20

BeansSow outdoors · Apr 29 – May 13

Sweet cornSow outdoors · Apr 29 – May 13

Cucumbers, squashSow outdoors · Apr 29 – May 13

Fall lettuce, spinachSow outdoors · Sep 2 – Sep 16

GarlicPlant cloves · Oct 14 – Nov 18

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 22) and first fall frost (Oct 28) 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 02638 came on Apr 3 — about the same time as the 1991–2020 average (Apr 4).

average
Apr 42026
Apr 3

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 7b in Massachusetts

563 plants native to the lower 48 states, recorded in Massachusetts, and rated by the USDA to survive 5 °F or colder — the bottom of zone 7b. 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 Dennis, MA.

Soil in Dennis, MA

The soil mapped at the center of ZIP 02638 is Ipswich — mucky peat, very poorly drained.

TextureMucky peattop layer

DrainageVery poorly drainedconsider raised beds

Organic matter64%high

Hydrologic groupA/Ddrains fast once dried out; wet otherwise

Farmland classNot prime farmlandUSDA classification

Map unit: Ipswich - Pawcatuck - Matunuck complex, 0 to 2 percent slopes, very frequently flooded.

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 02638; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Dennis, MA

Summer high81 °Faverage high, July

Winter low24 °Faverage low, January

Hot days2days a year at 90 °F or more

Freezing nights109nights a year at 32 °F or less

Growing degree days2,764base 50 °F — the season’s usable heat

Longest day15 h 13 mindaylight on June 21

Shortest day9 h 09 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation49.5 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: Hyannis Barnstable Municipal Airport, MA (6 mi away); precipitation: Yarmouth 2.3 Sse, MA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

026757a

Yarmouth Port, MA · 3 mi

026607a

South Dennis, MA · 3 mi

026417b

East Dennis, MA · 3 mi

026647a

South Yarmouth, MA · 4 mi

026377a

Cummaquid, MA · 4 mi

026707b

West Dennis, MA · 5 mi

026397b

Dennis Port, MA · 5 mi

026737a

West Yarmouth, MA · 6 mi

Massachusetts planting zones →

Questions about 02638

What planting zone is ZIP code 02638?

ZIP code 02638 (Dennis, MA) is in USDA hardiness zone 7b on the 2023 map: the coldest night of an average winter reaches 5 to 10 °F (−15 to −12.2 °C).

When is the last frost in Dennis, MA?

The median last spring frost (32 °F) near 02638 is April 22; after May 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Hyannis Barnstable Municipal Airport station.

When is the first frost in Dennis, MA?

The median first fall frost near 02638 is October 28, giving a median frost-free growing season of 188 days.

When should I plant tomatoes in 02638?

Start tomato seeds indoors around Feb 25 – Mar 11 and set transplants outside around Apr 29 – May 13, one to three weeks after the median last frost.

How much rain and snow does 02638 get?

About 49.5 inches of precipitation a year (NOAA 1991–2020 normals, Yarmouth 2.3 Sse station).

How hot do summers get in Dennis, MA?

The average high peaks at 81 °F in July, with about 2 days a year at 90 °F or more.

What kind of soil does 02638 have?

The USDA soil survey maps Ipswich at the center of ZIP 02638: mucky peat, very poorly drained.

Did spring come early in Dennis, MA in 2026?

Spring leaf-out near 02638 came on Apr 3 in 2026, about the same as the 1991–2020 average (Apr 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Dennis, MA?

Long-day onions: the longest day near 02638 is 15 h 13 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 02638 change?

Yes. The 2012 USDA map put 02638 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.