Frost dates / Connecticut / Waterbury

Frost dates in Waterbury, CT

The station on this page is MERIDEN MARKHAM MUNI AP, CT US (USW00054788), 11.3 miles from the city point. Population in the Census 2024 estimate is 115,908.

Zone 6bUSDA average annual extreme minimum -5°F to 0°F, from ZIP 06702 (0.5 miles from the city point used on this page).

Median last 32°F is April 26. Median first 32°F is October 16. The 50% growing-season length is 175 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 26	Median.
10%	May 9	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 4	Earlier date. A first 32°F on or before this day is uncommon.
50%	October 16	Median.
90%	November 1	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%	194
50%	175
90%	156

28°F threshold

	10%	50%	90%
Last, on or after	April 28	April 10	March 30
First, on or before	October 14	October 30	November 12
Season at least	218 days	198 days	179 days

36°F threshold

	10%	50%	90%
Last, on or after	May 21	May 7	April 24
First, on or before	September 26	October 6	October 19
Season at least	171 days	152 days	134 days

Station MERIDEN MARKHAM MUNI AP, CT US (USW00054788). Completeness flag R, 19 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 31.4 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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Waterbury, CT

Zone 6bAverage annual extreme minimum -5°F to 0°F

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

Connecticut. Nearest qualified station: MERIDEN MARKHAM MUNI AP, CT US (USW00054788), 11.3 miles. Median last 32°F April 26. Median first 32°F October 16. The 50% growing-season length is 175 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	May 9	April 26	April 11
First 32°F on or before	October 4	October 16	November 1

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.

A wall calendar surrounded by vegetables, herbs, seed packets, and watering cans.

Planting calendar

Frost dates for Connecticut 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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