Frost dates / Massachusetts / Worcester

Frost dates in Worcester, MA

The station on this page is WORCESTER RGNL AP, MA US (USW00094746), 3.3 miles from the city point. Population in the Census 2024 estimate is 211,286.

Zone 6aUSDA average annual extreme minimum -10°F to -5°F, from ZIP 01608 (0.6 miles from the city point used on this page).

Median last 32°F is April 23. Median first 32°F is October 21. The 50% growing-season length is 181 days. The green band runs from the median last frost to the median first frost. Thin ticks mark the 10%, 50%, and 90% dates.

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Last 32°F in spring

NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.

Probability	Date	How to read it
90%	April 11	Earlier date. A last 32°F on or after this day is common.
50%	April 23	Median.
10%	May 5	Later date. A last 32°F on or after this day is uncommon.

First 32°F in fall

NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.

Probability	Date	How to read it
10%	October 6	Earlier date. A first 32°F on or before this day is uncommon.
50%	October 21	Median.
90%	November 3	Later date. A first 32°F on or before this day is common.

32°F growing-season length

Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.

Probability the season is at least this long	Days
10%	198
50%	181
90%	160

28°F threshold

	10%	50%	90%
Last, on or after	April 22	April 11	April 1
First, on or before	October 17	November 1	November 15
Season at least	222 days	205 days	185 days

36°F threshold

	10%	50%	90%
Last, on or after	May 19	May 4	April 23
First, on or before	September 28	October 9	October 23
Season at least	175 days	158 days	139 days

Station WORCESTER RGNL AP, MA US (USW00094746). Completeness flag S, 28 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 100%. Freeze dates are conditional on that threshold occurring. Elevation 304.8 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

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Worcester, MA

Zone 6aAverage annual extreme minimum -10°F to -5°F

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Massachusetts. Nearest qualified station: WORCESTER RGNL AP, MA US (USW00094746), 3.3 miles. Median last 32°F April 23. Median first 32°F October 21. The 50% growing-season length is 181 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	May 5	April 23	April 11
First 32°F on or before	October 6	October 21	November 3

Column order matches the NCEI file: for the last freeze, 10% is the later date and 90% is the earlier date. How to read the probabilities.

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Planting calendar

Frost dates for Massachusetts are above. Planting windows appear for states with a cited extension guide. The fall and seed tools use the numbers you enter and the station dates.

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