Frost dates / Connecticut / Hartford

Frost dates in Hartford, CT

The station on this page is HARTFORD BRAINARD FLD, CT US (USW00014752), 2.6 miles from the city point. Population in the Census 2024 estimate is 122,129.

Zone 6bUSDA average annual extreme minimum -5°F to 0°F, from ZIP 06103 (0.6 miles from the city point used on this page).

Median last 32°F is April 17. Median first 32°F is October 26. The 50% growing-season length is 191 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 1	Earlier date. A last 32°F on or after this day is common.
50%	April 17	Median.
10%	May 1	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 12	Earlier date. A first 32°F on or before this day is uncommon.
50%	October 26	Median.
90%	November 7	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%	212
50%	191
90%	169

28°F threshold

	10%	50%	90%
Last, on or after	April 21	April 3	March 21
First, on or before	October 22	November 5	November 20
Season at least	237 days	216 days	193 days

36°F threshold

	10%	50%	90%
Last, on or after	May 14	April 30	April 17
First, on or before	October 2	October 14	October 29
Season at least	186 days	167 days	148 days

Station HARTFORD BRAINARD FLD, CT US (USW00014752). 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 5.8 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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Hartford, 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: HARTFORD BRAINARD FLD, CT US (USW00014752), 2.6 miles. Median last 32°F April 17. Median first 32°F October 26. The 50% growing-season length is 191 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	May 1	April 17	April 1
First 32°F on or before	October 12	October 26	November 7

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 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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