Haddam, CT climate
Haddam has chilly winters and pleasant summers. A typical July afternoon reaches 84°, a January night drops to 20°.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Haddam feels like
Winter
Spring
Summer
Fall
Haddam weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 37° | 20° | 3.7" | 20° – 35° |
| February | 40° | 21° | 3.1" | 16° – 37° |
| March | 47° | 28° | 4.1" | 31° – 46° |
| April | 59° | 37° | 4.1" | 44° – 53° |
| May | 70° | 47° | 3.4" | 53° – 63° |
| June | 78° | 56° | 4.3" | 64° – 70° |
| July | 84° | 63° | 3.7" | 69° – 77° |
| August | 82° | 61° | 4.0" | 68° – 75° |
| September | 75° | 54° | 4.1" | 61° – 69° |
| October | 63° | 42° | 4.5" | 49° – 60° |
| November | 52° | 33° | 3.9" | 38° – 47° |
| December | 42° | 25° | 4.3" | 27° – 44° |
| Year | 61° | 41° | 47.3" |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Haddam
Haddam gets 47 inches of rain and melted snow a year. October is the wettest month and February the driest.
About 175 frost-free days a year
In half of years the last 32° night comes by April 26 and the first one by October 16. That leaves about 175 frost-free days for gardens, shorter than 54% of U.S. towns.
Heating and cooling a home in Haddam
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Haddam, 89% of that work is heating and 11% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Haddam and its neighbors
Haddam borders 6 towns with climate data. January nights across them vary by 1.1°. East Hampton has the coldest January nights (19°) and Middletown the hottest July afternoons (85°). Haddam’s January low is 20° and its July high 84°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Haddam compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Haddam averaged 1.9° warmer than the 1900s. The biggest change is in December (+3.4°). The shift is larger than in 92% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Haddam’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 16° to 37°. June is the most reliable, staying within 6°.
Common questions about Haddam’s climate
What is the coldest month in Haddam?
January, with a typical high of 37° and a low of 20°.
What is the hottest month in Haddam?
July, with a typical high of 84° and a low of 63°. About 15 days a year reach 90°.
When is the first frost in Haddam?
In half of years the first 32° night comes by October 16, and the last spring frost by April 26.
What is the rainiest month in Haddam?
October, with 4.5 inches of rain and melted snow. The year totals 47 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Haddam itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Meriden Markham Municipal Airport, CT (15 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.