Photo: Kenneth C. Zirkel · CC BY-SA 4.0Neither notably warm, cold, wet nor dry, Killingworth sits near the middle of U.S. towns
Midsummer highs settle at about 83°. Its yearly precipitation tops that of 71% of U.S. towns. Compared with 1901–2000, the average now sits 1.8° higher. The frost-free window for a garden runs roughly April 26 to October 16.
A year in Killingworth at a glance
Each month’s typical high and low, and what it brings.
What stands out about Killingworth’s climate
Compared with towns across the U.S., with Killingworth’s place in Connecticut beside it.
What a year in Killingworth feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 175 frost-free days a year
In half of years the last 32° night comes by April 26 and the first by October 16. Frost and day counts come from NOAA’s station at Meriden Markham Muni Airport, 16 miles from the town’s center, 270 ft lower.
The 2023 USDA map puts Killingworth’s center in zone 6b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 0°. 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 Killingworth
89% 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 Meriden Markham Muni Airport.
Living with Killingworth’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
175 frost-free days in zone 6b. The last frost comes by Apr 26 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 16.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 73 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Killingworth from natural hazards, river flooding is the largest share (74%); heat waves, cold waves, winter storms and ice storms together are 3%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Killingworth and its neighbors
Durham has the coldest January nights next door (19°, 1° colder). Differences under a degree are within what 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 Killingworth averaged 1.8° warmer than the 1900s. The biggest change is in December (+3.3°).
A bigger shift than in 78% 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 Killingworth compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Killingworth’s place among Connecticut’s.
Killingworth weather by month
Highs, lows and precipitation from NOAA’s grid at Killingworth’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 38° | 20° | 3.6" | 20° – 35° |
| February | 40° | 22° | 3.1" | 18° – 37° |
| March | 47° | 28° | 4.2" | 32° – 46° |
| April | 59° | 37° | 4.3" | 44° – 52° |
| May | 69° | 47° | 3.5" | 53° – 63° |
| June | 77° | 57° | 4.3" | 64° – 69° |
| July | 83° | 63° | 3.7" | 69° – 76° |
| August | 81° | 62° | 3.8" | 68° – 75° |
| September | 74° | 54° | 4.2" | 62° – 69° |
| October | 63° | 43° | 4.4" | 50° – 59° |
| November | 52° | 34° | 3.9" | 39° – 47° |
| December | 43° | 26° | 4.3" | 28° – 45° |
| Year | 61° | 41° | 47.2" |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 18° to 37°. June is the most reliable, staying within 6°.
Where Killingworth’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 Killingworth’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Meriden Markham Muni Airport, 16 miles from the town’s center, 270 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 Killingworth’s climate
What is the weather like in Killingworth?
A typical July afternoon reaches 83°, a January night drops to 20°. Colder January nights than 57% of U.S. towns; cooler July afternoons than 70% of U.S. towns.
How cold does it get in Killingworth in winter?
January nights average 20°. About 129 nights a year reach 32° or below and 4 reach 0° or below. In the coldest January of the last 30 years the month averaged 20°.
How hot does it get in Killingworth?
July, with a typical high of 83° and a low of 63°. About 15 days a year reach 90° (Meriden Markham Muni Airport).
When is the first and last frost in Killingworth?
In half of years the last spring frost (32°) comes by April 26 and the first fall frost by October 16, about 175 frost-free days, at Meriden Markham Muni Airport.
What growing zone is Killingworth in?
Zone 6b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 0°.
What is the best time of year to visit Killingworth?
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 Killingworth getting warmer?
Yes: 1991–2020 averaged 1.8° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 78% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Killingworth.
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.