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

Planting zone for 02238 — Cambridge, MA

ZIP code 02238 (Cambridge, Middlesex County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 4 and the first fall frost November 9.

Where ZIP 02238 is

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.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostApr 4
First frostNov 9
2012 zone6b

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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Cambridge, 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 Cambridge, MA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 4median — 50% chance of a later frost
Safe for tender plantsApril 17only 10% chance of frost after
First fall frostNovember 9median — 10% chance by Oct 29
Growing season218 daysfrost-free, median

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

From the NOAA station Boston Logan Intl Airport, MA — 5 miles away, elevation 13 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 02238

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 21 – Mar 7
SpinachSow outdoors · Feb 21 – Mar 14
Broccoli, cabbageStart indoors · Jan 24 – Feb 7
Broccoli, cabbageTransplant · Mar 14 – Mar 28
Onion setsPlant outdoors · Mar 7 – Mar 21
PotatoesPlant outdoors · Mar 14 – Mar 28
LettuceSow outdoors · Mar 7 – Mar 21
Carrots, beetsSow outdoors · Mar 14 – Mar 28
TomatoesStart indoors · Feb 7 – Feb 21
TomatoesTransplant · Apr 11 – Apr 25
Peppers, eggplantStart indoors · Jan 24 – Feb 7
Peppers, eggplantTransplant · Apr 18 – May 2
BeansSow outdoors · Apr 11 – Apr 25
Sweet cornSow outdoors · Apr 11 – Apr 25
Cucumbers, squashSow outdoors · Apr 11 – Apr 25
Fall lettuce, spinachSow outdoors · Sep 14 – Sep 28
GarlicPlant cloves · Oct 26 – Nov 30
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 4) and first fall frost (Nov 9) 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 02238 came on Apr 1 — 4 days earlier than the 1991–2020 average (Apr 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 6b in Massachusetts

548 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 6b. Each links to its USDA PLANTS profile.

Trees 66

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 109

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 black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 188

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 159

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 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °F

Vines 8

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °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 Cambridge, MA.

Soil in Cambridge, MA

The soil mapped at the center of ZIP 02238 is Merrimac — fine sandy loam, somewhat excessively drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH5.1strongly acidic; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter4.12%moderate
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Merrimac-Urban land complex, 0 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 02238; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cambridge, MA

Summer high82 °Faverage high, July
Winter low23 °Faverage low, January
Hot days14days a year at 90 °F or more
Freezing nights92nights a year at 32 °F or less
Growing degree days3,050base 50 °F — the season’s usable heat
Longest day15 h 17 mindaylight on June 21
Shortest day9 h 04 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation49.3 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 37 °F, low 23 °F 37°23° JanFebruary: average high 39 °F, low 25 °F 39°25° FebMarch: average high 46 °F, low 31 °F 46°31° MarApril: average high 56 °F, low 41 °F 56°41° AprMay: average high 67 °F, low 50 °F 67°50° MayJune: average high 76 °F, low 60 °F 76°60° JunJuly: average high 82 °F, low 66 °F 82°66° JulAugust: average high 80 °F, low 65 °F 80°65° AugSeptember: average high 73 °F, low 58 °F 73°58° SepOctober: average high 62 °F, low 48 °F 62°48° OctNovember: average high 52 °F, low 38 °F 52°38° NovDecember: average high 42 °F, low 29 °F 42°29° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.72 in precipitation 3.7 JanFebruary: 3.74 in precipitation 3.7 FebMarch: 4.52 in precipitation 4.5 MarApril: 4.37 in precipitation 4.4 AprMay: 3.66 in precipitation 3.7 MayJune: 4.38 in precipitation 4.4 JunJuly: 3.46 in precipitation 3.5 JulAugust: 3.72 in precipitation 3.7 AugSeptember: 3.92 in precipitation 3.9 SepOctober: 4.78 in precipitation 4.8 OctNovember: 4.05 in precipitation 4.0 NovDecember: 4.97 in precipitation 5.0 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Boston Logan Intl Airport, MA (5 mi away); precipitation: Cambridge 0.9 Nnw, MA (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

021437a
Somerville, MA · <1 mi
021396b
Cambridge, MA · <1 mi
021636b
Boston, MA · 1 mi
021417a
Cambridge, MA · 1 mi
021457a
Somerville, MA · 1 mi
021427a
Cambridge, MA · 2 mi
021386b
Cambridge, MA · 2 mi
021346b
Allston, MA · 2 mi

All 6 ZIP codes in Cambridge → · Massachusetts planting zones →

Questions about 02238

What planting zone is ZIP code 02238?

ZIP code 02238 (Cambridge, MA) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Cambridge, MA?

The median last spring frost (32 °F) near 02238 is April 4; after April 17 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Boston Logan Intl Airport station.

When is the first frost in Cambridge, MA?

The median first fall frost near 02238 is November 9, giving a median frost-free growing season of 218 days.

When should I plant tomatoes in 02238?

Start tomato seeds indoors around Feb 7 – Feb 21 and set transplants outside around Apr 11 – Apr 25, one to three weeks after the median last frost.

How much rain and snow does 02238 get?

About 49.3 inches of precipitation a year (NOAA 1991–2020 normals, Cambridge 0.9 Nnw station).

How hot do summers get in Cambridge, MA?

The average high peaks at 82 °F in July, with about 14 days a year at 90 °F or more.

What kind of soil does 02238 have?

The USDA soil survey maps Merrimac at the center of ZIP 02238: fine sandy loam, somewhat excessively drained, pH about 5.1 (strongly acidic).

Did spring come early in Cambridge, MA in 2026?

Spring leaf-out near 02238 came on Apr 1 in 2026, 4 days earlier than the 1991–2020 average (Apr 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cambridge, MA?

Long-day onions: the longest day near 02238 is 15 h 17 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).