When is the last frost in Marlborough, MA?

The average last spring frost (50% probability of 32°F) in Marlborough is around May 2, based on NOAA/NCEI 1991–2020 normals at the Maynard 2, MA station (7.7 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in Marlborough?

The average first fall frost in Marlborough, MA is around October 6, giving roughly a 156-day frost-free growing season.

What planting zone is Marlborough, MA?

Marlborough is in USDA plant hardiness zone 6b (average annual extreme minimum temperature -5 to 0°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Marlborough?

In Marlborough, MA the warmest month is July (avg high 81.8°F) and the coldest is January (avg low 17.5°F). It averages about 47.3″ of precipitation a year and 45.7″ of snow.

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Marlborough, MA Planting Calendar & Frost Dates

USDA hardiness zone 6b · ZIP 01752 · elevation 55′ · NOAA & USDA data

Marlborough is in USDA hardiness zone 6b (winters can dip to -5 to 0°F), with a growing season of about 156 days between the average last spring frost (May 2) and first fall frost (October 6). The warmest month is July (avg high 81.8°F); the coldest is January (avg low 17.5°F). It averages 47.3″ of precipitation a year and 45.7″ of snow, mostly mid-winter. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp -5 to 0°F

Last spring frost

May 2

avg (50% prob, 32°F)

First fall frost

October 6

avg (50% prob, 32°F)

Growing season

156 days

frost-free window

Warmest month

July

avg high 81.8°F

Month-by-month typical weather in Marlborough

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Natick, MA (11.4 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	35.2	17.5	26.4	3.4	13.8
February	38.2	17.6	27.9	3.1	8.9
March	46.1	25.4	35.7	4	8.2
April	58	35.1	46.6	4.1	2.2
May	67.7	45.6	56.7	3.8	0
June	76.5	55.9	66.2	4.1	0
July	81.8	61.7	71.8	3.9	0
August	80.4	59.4	69.9	3.8	0
September	73	51.8	62.4	4.2	0
October	61.7	39.7	50.7	4.8	0
November	51.3	31.1	41.2	3.7	1.1
December	40.7	22.9	31.8	4.4	11.5

What to plant when in Marlborough

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: March 21 · Transplant out: May 9
Peppers	warm	Start seeds indoors: March 7 · Transplant out: May 16
Cucumbers	warm	Direct sow: May 9
Zucchini / squash	warm	Direct sow: May 9
Bush beans	warm	Direct sow: May 9
Sweet corn	warm	Direct sow: May 9
Basil	warm	Transplant out: May 9
Peas	cool	Sow (spring): March 28 · Sow (fall): August 11
Spinach	cool	Sow (spring): March 21 · Sow (fall): August 11
Lettuce	cool	Sow (spring): April 4 · Sow (fall): August 11
Kale	cool	Transplant (spring): April 11 · Sow (fall): July 28
Broccoli	cool	Transplant (spring): April 18
Carrots	cool	Sow (spring): April 11 · Sow (fall): July 28
Onions	cool	Transplant (spring): April 4
Potatoes	cool	Plant seed potatoes: April 18
Radishes	cool	Sow (spring): April 4 · Sow (fall): August 25

Dates are computed from Marlborough's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

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Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

Nearby cities in Massachusetts

Waltham, MA Leominster, MA Worcester, MA Newton, MA Cambridge, MA Fitchburg, MA Woburn, MA Medford, MA

Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — Maynard 2, MA, 7.7 mi (confidence: high). Monthly weather normals: Natick, MA, 11.4 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.