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

Planting zone for 02420 — Lexington, MA

ZIP code 02420 (Lexington, Middlesex County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 28 and the first fall frost October 10.

Where ZIP 02420 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.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostApr 28
First frostOct 10
2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Lexington, 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 Lexington, MA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 28median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 10median — 10% chance by Sep 28
Growing season165 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 12 and returns around October 25.

From the NOAA station Bedford Hanscom Field, MA — 4 miles away, elevation 135 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 02420

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 17 – Mar 31
SpinachSow outdoors · Mar 17 – Apr 7
Broccoli, cabbageStart indoors · Feb 17 – Mar 3
Broccoli, cabbageTransplant · Apr 7 – Apr 21
Onion setsPlant outdoors · Mar 31 – Apr 14
PotatoesPlant outdoors · Apr 7 – Apr 21
LettuceSow outdoors · Mar 31 – Apr 14
Carrots, beetsSow outdoors · Apr 7 – Apr 21
TomatoesStart indoors · Mar 3 – Mar 17
TomatoesTransplant · May 5 – May 19
Peppers, eggplantStart indoors · Feb 17 – Mar 3
Peppers, eggplantTransplant · May 12 – May 26
BeansSow outdoors · May 5 – May 19
Sweet cornSow outdoors · May 5 – May 19
Cucumbers, squashSow outdoors · May 5 – May 19
Fall lettuce, spinachSow outdoors · Aug 15 – Aug 29
GarlicPlant cloves · Sep 26 – Oct 31
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 28) and first fall frost (Oct 10) 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 02420 came on Apr 4 — 4 days earlier than the 1991–2020 average (Apr 8).

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 Lexington, MA.

Soil in Lexington, MA

The soil mapped at the center of ZIP 02420 is Wareham — loamy fine sand, poorly drained.

TextureLoamy fine sanddrains and warms fast; dries out and needs more feeding
pH5.1strongly acidic; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter3.5%moderate
Hydrologic groupA/Ddrains fast once dried out; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Wareham loamy fine sand, 0 to 5 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 02420; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Lexington, MA

Summer high85 °Faverage high, July
Winter low18 °Faverage low, January
Hot days15days a year at 90 °F or more
Freezing nights139nights a year at 32 °F or less
Growing degree days2,906base 50 °F — the season’s usable heat
Longest day15 h 18 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)
Precipitation42.6 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 37 °F, low 18 °F 37°18° JanFebruary: average high 39 °F, low 19 °F 39°19° FebMarch: average high 48 °F, low 27 °F 48°27° MarApril: average high 60 °F, low 37 °F 60°37° AprMay: average high 70 °F, low 47 °F 70°47° MayJune: average high 79 °F, low 56 °F 79°56° JunJuly: average high 85 °F, low 62 °F 85°62° JulAugust: average high 84 °F, low 60 °F 84°60° AugSeptember: average high 76 °F, low 52 °F 76°52° SepOctober: average high 64 °F, low 41 °F 64°41° OctNovember: average high 52 °F, low 32 °F 52°32° NovDecember: average high 42 °F, low 24 °F 42°24° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.90 in precipitation 2.9 JanFebruary: 2.69 in precipitation 2.7 FebMarch: 3.85 in precipitation 3.9 MarApril: 3.84 in precipitation 3.8 AprMay: 3.36 in precipitation 3.4 MayJune: 3.72 in precipitation 3.7 JunJuly: 3.51 in precipitation 3.5 JulAugust: 3.47 in precipitation 3.5 AugSeptember: 3.54 in precipitation 3.5 SepOctober: 4.24 in precipitation 4.2 OctNovember: 3.72 in precipitation 3.7 NovDecember: 3.76 in precipitation 3.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Bedford Hanscom Field, MA (4 mi away); precipitation: Bedford Hanscom Field, MA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

024216b
Lexington, MA · 2 mi
018036b
Burlington, MA · 3 mi
024756b
Arlington Heights, MA · 3 mi
018056b
Burlington, MA · 3 mi
017316b
Hanscom Afb, MA · 3 mi
018136b
Woburn, MA · 4 mi
018156b
Woburn, MA · 4 mi
018886b
Woburn, MA · 4 mi

All 2 ZIP codes in Lexington → · Massachusetts planting zones →

Questions about 02420

What planting zone is ZIP code 02420?

ZIP code 02420 (Lexington, 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 Lexington, MA?

The median last spring frost (32 °F) near 02420 is April 28; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Bedford Hanscom Field station.

When is the first frost in Lexington, MA?

The median first fall frost near 02420 is October 10, giving a median frost-free growing season of 165 days.

When should I plant tomatoes in 02420?

Start tomato seeds indoors around Mar 3 – Mar 17 and set transplants outside around May 5 – May 19, one to three weeks after the median last frost.

How much rain and snow does 02420 get?

About 42.6 inches of precipitation a year (NOAA 1991–2020 normals, Bedford Hanscom Field station).

How hot do summers get in Lexington, MA?

The average high peaks at 85 °F in July, with about 15 days a year at 90 °F or more.

What kind of soil does 02420 have?

The USDA soil survey maps Wareham at the center of ZIP 02420: loamy fine sand, poorly drained, pH about 5.1 (strongly acidic).

Did spring come early in Lexington, MA in 2026?

Spring leaf-out near 02420 came on Apr 4 in 2026, 4 days earlier than the 1991–2020 average (Apr 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Lexington, MA?

Long-day onions: the longest day near 02420 is 15 h 18 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 02420 change?

Yes. The 2012 USDA map put 02420 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.