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

Planting zone for 02646 — Harwich Port, MA

ZIP code 02646 (Harwich Port, Barnstable County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 13 and the first fall frost November 3.

Where ZIP 02646 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 13
First frostNov 3
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 Harwich Port, 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 Harwich Port, MA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 13median — 50% chance of a later frost
Safe for tender plantsApril 26only 10% chance of frost after
First fall frostNovember 3median — 10% chance by Oct 22
Growing season204 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 1 and returns around November 17.

From the NOAA station W Harwich, MA — 2 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 02646

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 2 – Mar 16
SpinachSow outdoors · Mar 2 – Mar 23
Broccoli, cabbageStart indoors · Feb 2 – Feb 16
Broccoli, cabbageTransplant · Mar 23 – Apr 6
Onion setsPlant outdoors · Mar 16 – Mar 30
PotatoesPlant outdoors · Mar 23 – Apr 6
LettuceSow outdoors · Mar 16 – Mar 30
Carrots, beetsSow outdoors · Mar 23 – Apr 6
TomatoesStart indoors · Feb 16 – Mar 2
TomatoesTransplant · Apr 20 – May 4
Peppers, eggplantStart indoors · Feb 2 – Feb 16
Peppers, eggplantTransplant · Apr 27 – May 11
BeansSow outdoors · Apr 20 – May 4
Sweet cornSow outdoors · Apr 20 – May 4
Cucumbers, squashSow outdoors · Apr 20 – May 4
Fall lettuce, spinachSow outdoors · Sep 8 – Sep 22
GarlicPlant cloves · Oct 20 – Nov 24
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 13) and first fall frost (Nov 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 02646 came on Apr 6 — about the same time as the 1991–2020 average (Apr 6).

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 Harwich Port, MA

The soil mapped at the center of ZIP 02646 is Carver — slightly decomposed plant material, excessively drained.

TextureSlightly decomposed plant materialtop layer
DrainageExcessively drainednatural drainage class
Organic matter80%high
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Carver coarse sand, 3 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 02646; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Harwich Port, MA

Summer high78 °Faverage high, July
Winter low24 °Faverage low, February
Hot days1days a year at 90 °F or more
Freezing nights94nights a year at 32 °F or less
Growing degree days2,502base 50 °F — the season’s usable heat
Longest day15 h 12 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)
Precipitation46.3 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 38 °F, low 25 °F 38°25° JanFebruary: average high 38 °F, low 24 °F 38°24° FebMarch: average high 44 °F, low 30 °F 44°30° MarApril: average high 52 °F, low 39 °F 52°39° AprMay: average high 62 °F, low 48 °F 62°48° MayJune: average high 71 °F, low 58 °F 71°58° JunJuly: average high 78 °F, low 65 °F 78°65° JulAugust: average high 78 °F, low 64 °F 78°64° AugSeptember: average high 71 °F, low 57 °F 71°57° SepOctober: average high 62 °F, low 47 °F 62°47° OctNovember: average high 52 °F, low 37 °F 52°37° NovDecember: average high 43 °F, low 30 °F 43°30° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.84 in precipitation 3.8 JanFebruary: 3.68 in precipitation 3.7 FebMarch: 4.32 in precipitation 4.3 MarApril: 4.10 in precipitation 4.1 AprMay: 3.50 in precipitation 3.5 MayJune: 3.29 in precipitation 3.3 JunJuly: 2.77 in precipitation 2.8 JulAugust: 3.36 in precipitation 3.4 AugSeptember: 3.93 in precipitation 3.9 SepOctober: 4.72 in precipitation 4.7 OctNovember: 4.00 in precipitation 4.0 NovDecember: 4.83 in precipitation 4.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: W Harwich, MA (2 mi away); precipitation: W Harwich, MA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

026717b
West Harwich, MA · 2 mi
026457b
Harwich, MA · 2 mi
026617b
South Harwich, MA · 2 mi
026597b
South Chatham, MA · 3 mi
026397b
Dennis Port, MA · 3 mi
026697b
West Chatham, MA · 4 mi
026337b
Chatham, MA · 5 mi
026607a
South Dennis, MA · 5 mi

Massachusetts planting zones →

Questions about 02646

What planting zone is ZIP code 02646?

ZIP code 02646 (Harwich Port, 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 Harwich Port, MA?

The median last spring frost (32 °F) near 02646 is April 13; after April 26 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, W Harwich station.

When is the first frost in Harwich Port, MA?

The median first fall frost near 02646 is November 3, giving a median frost-free growing season of 204 days.

When should I plant tomatoes in 02646?

Start tomato seeds indoors around Feb 16 – Mar 2 and set transplants outside around Apr 20 – May 4, one to three weeks after the median last frost.

How much rain and snow does 02646 get?

About 46.3 inches of precipitation a year (NOAA 1991–2020 normals, W Harwich station).

How hot do summers get in Harwich Port, MA?

The average high peaks at 78 °F in July, with about 1 days a year at 90 °F or more.

What kind of soil does 02646 have?

The USDA soil survey maps Carver at the center of ZIP 02646: slightly decomposed plant material, excessively drained.

Did spring come early in Harwich Port, MA in 2026?

Spring leaf-out near 02646 came on Apr 6 in 2026, about the same as the 1991–2020 average (Apr 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Harwich Port, MA?

Long-day onions: the longest day near 02646 is 15 h 12 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 02646 change?

Yes. The 2012 USDA map put 02646 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.