Summers in Groton are cooler than in 95% of U.S. towns
In January the night’s low is typically 15°. Winter nights are cold: in January they are colder than in 86% of U.S. towns. The latest 30-year average runs 1.1° warmer than 1901–2000’s, with February up the most. Radiators earn their keep from October to April, the months that average under 50°.
A year in Groton at a glance
Each month’s typical high and low, and what it brings.
What stands out about Groton’s climate
Compared with towns across the U.S., with Groton’s place in New York beside it.
What a year in Groton feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 154 frost-free days a year
In half of years the last 32° night comes by May 7 and the first by October 8. Frost and day counts come from NOAA’s station at Freeville 1 Ne, NY, 5 miles from the town’s center, at about the same height.
The 2023 USDA map puts Groton’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −12°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 63 inches of snow a winter
Snow, measured at Ithaca Cornell Univ, NY, falls mostly in January. Precipitation (rain plus melted snow) adds up to 42 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 166 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Groton
96% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Freeville 1 Ne, NY.
Living with Groton’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
154 frost-free days in zone 5b. The last frost comes by May 7 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 8.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September.
Parks & trails →Of the yearly building losses FEMA expects in Groton from natural hazards, river flooding is the largest share (84%); heat waves, cold waves, winter storms and ice storms together are 3%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Groton and similar climates
TownRatings has no climate map of the towns around Groton yet.
Climates most like Groton’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Groton, NY | 15° | 79° | 42" | 63" |
| Treasure Lake, PA | 17° | 80° | 45" | 53" |
| Bennington, VT | 13° | 81° | 44" | 75" |
| Augusta, ME | 10° | 80° | 45" | 69" |
| Jaffrey, NH | 13° | 80° | 47" | 73" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Groton averaged 1.1° warmer than the 1900s. The biggest change is in February (+2.6°).
A smaller shift than in 72% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Groton compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Groton’s place among New York’s.
Groton weather by month
Highs, lows and precipitation from NOAA’s grid at Groton’s center; snow, wet days and snow on the ground from Ithaca Cornell Univ, NY. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 30° | 15° | 2.7" | 16.6" | 16 | 21 | 13° – 31° |
| February | 33° | 16° | 2.3" | 14.5" | 13 | 20 | 10° – 33° |
| March | 41° | 23° | 3.0" | 12.0" | 14 | 13 | 24° – 45° |
| April | 54° | 33° | 3.5" | 2.8" | 14 | 1 | 37° – 49° |
| May | 67° | 45° | 3.6" | 0.0" | 15 | 0 | 50° – 61° |
| June | 75° | 54° | 4.4" | 0.0" | 14 | 0 | 61° – 69° |
| July | 79° | 59° | 4.1" | 0.0" | 13 | 0 | 65° – 72° |
| August | 78° | 56° | 4.0" | 0.0" | 12 | 0 | 64° – 71° |
| September | 71° | 50° | 4.2" | 0.0" | 12 | 0 | 58° – 65° |
| October | 58° | 39° | 4.0" | 0.2" | 15 | 0 | 44° – 55° |
| November | 46° | 31° | 3.2" | 4.6" | 14 | 4 | 33° – 44° |
| December | 35° | 22° | 3.2" | 12.2" | 16 | 14 | 20° – 39° |
| Year | 55° | 37° | 42.2" | 62.9" | 166 | 73 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 10° to 33°. August is the most reliable, staying within 7°.
Where Groton’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Groton’s center.
- Snow: Ithaca Cornell Univ, NY.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Freeville 1 Ne, NY, 5 miles from the town’s center, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Groton’s climate
What is the weather like in Groton?
A typical July afternoon reaches 79°, a January night drops to 15°, and about 63 inches of snow falls in a normal winter. Colder January nights than 86% of U.S. towns; cooler July afternoons than 95% of U.S. towns.
How cold does it get in Groton in winter?
January nights average 15°. About 156 nights a year reach 32° or below and 16 reach 0° or below. In the coldest January of the last 30 years the month averaged 13°.
How much snow does Groton get?
About 63 inches in a normal winter at Ithaca Cornell Univ, NY, most of it in January, with snow on the ground about 73 days a year.
How hot does it get in Groton?
July, with a typical high of 79° and a low of 59°. About 3 days a year reach 90° (Freeville 1 Ne, NY).
When is the first and last frost in Groton?
In half of years the last spring frost (32°) comes by May 7 and the first fall frost by October 8, about 154 frost-free days, at Freeville 1 Ne, NY.
What growing zone is Groton in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −12°.
What is the best time of year to visit Groton?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Groton getting warmer?
Yes: 1991–2020 averaged 1.1° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 72% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Groton.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.