Photo: Dmadeo · CC BY-SA 3.0Guilford’s winters are colder than most of the U.S.; July afternoons average 84°
A typical July afternoon reaches 84°, a January night drops to 20°.
A year in Guilford at a glance
Each month’s typical high and low, and what it brings.
What stands out about Guilford’s climate
Compared with towns across the U.S., with Guilford’s place in Connecticut beside it.
What a year in Guilford feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 193 frost-free days a year
In half of years the last 32° night comes by April 17 and the first by October 27. Frost and day counts come from NOAA’s station at New Haven Tweed Airport, 11 miles from the town’s center, 150 ft lower.
The 2023 USDA map puts Guilford’s center in zone 7a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 1°. 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 47 inches of rain a year
October is the wettest month and February the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Guilford
88% 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 New Haven Tweed Airport.
Living with Guilford’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
193 frost-free days in zone 7a. The last frost comes by Apr 17 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 27.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 156 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Guilford from natural hazards, river flooding is the largest share (59%); heat waves, cold waves, winter storms and ice storms together are 3%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Guilford and its neighbors
Every town next door is within a degree of Guilford in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Guilford averaged 1.7° warmer than the 1900s. The biggest change is in December (+3.3°).
A bigger shift than in 75% 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 Guilford compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Guilford’s place among Connecticut’s.
Guilford weather by month
Highs, lows and precipitation from NOAA’s grid at Guilford’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 38° | 20° | 3.5" | 20° – 35° |
| February | 40° | 21° | 3.1" | 17° – 37° |
| March | 47° | 28° | 4.2" | 32° – 46° |
| April | 59° | 37° | 4.3" | 44° – 53° |
| May | 69° | 47° | 3.6" | 53° – 63° |
| June | 78° | 57° | 4.2" | 64° – 70° |
| July | 84° | 63° | 3.9" | 69° – 77° |
| August | 82° | 62° | 3.7" | 68° – 76° |
| September | 75° | 55° | 4.1" | 62° – 69° |
| October | 64° | 43° | 4.5" | 50° – 60° |
| November | 52° | 34° | 3.8" | 38° – 47° |
| December | 42° | 26° | 4.2" | 28° – 45° |
| Year | 61° | 41° | 47.0" |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 17° to 37°. June is the most reliable, staying within 6°.
Where Guilford’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 Guilford’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: New Haven Tweed Airport, 11 miles from the town’s center, 150 ft lower; 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 Guilford’s climate
What is the weather like in Guilford?
A typical July afternoon reaches 84°, a January night drops to 20°. Colder January nights than 58% of U.S. towns; cooler July afternoons than 65% of U.S. towns.
How cold does it get in Guilford in winter?
January nights average 20°. About 102 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 20°.
How hot does it get in Guilford?
July, with a typical high of 84° and a low of 63°. About 6 days a year reach 90° (New Haven Tweed Airport).
When is the first and last frost in Guilford?
In half of years the last spring frost (32°) comes by April 17 and the first fall frost by October 27, about 193 frost-free days, at New Haven Tweed Airport.
What growing zone is Guilford in?
Zone 7a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 1°.
What is the best time of year to visit Guilford?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Guilford getting warmer?
Yes: 1991–2020 averaged 1.7° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 75% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Guilford.
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.