Photo: Dough4872 · CC BY-SA 4.0Hartly’s winters are milder and less snowy than most of the U.S.
A typical July afternoon reaches 88°, a January night drops to 25°, and about 13 inches of snow falls in a normal winter.
A year in Hartly at a glance
Each month’s typical high and low, and what it brings.
What stands out about Hartly’s climate
Compared with towns across the U.S., with Hartly’s place in Delaware beside it.
What a year in Hartly feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 214 frost-free days a year
In half of years the last 32° night comes by April 4 and the first by November 4. Frost and day counts come from NOAA’s station at Dover, DE, 11 miles from the town’s center, at about the same height.
The 2023 USDA map puts Hartly’s center in zone 7b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 6°. 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 13 inches of snow a winter
Snow, measured at Dover, DE, falls mostly in February. Precipitation (rain plus melted snow) adds up to 44 inches a year; July is the wettest month and February the driest. Rain or snow falls on about 110 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Hartly
76% of the work is heating. Months averaging under 55° run from November 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 Dover, DE.
Living with Hartly’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
214 frost-free days in zone 7b. The last frost comes by Apr 4 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Nov 4.
Months with highs of 62–84° and lows of 40° or more: April, May, June, September and October.
Parks & trails →Of the yearly building losses FEMA expects in Hartly from natural hazards, river flooding is the largest share (40%); heat waves, cold waves, winter storms and ice storms together are 26%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Hartly and similar climates
TownRatings has no climate map of the towns around Hartly yet.
Climates most like Hartly’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 |
|---|---|---|---|---|
| Hartly, DE | 25° | 88° | 44" | 13" |
| Hurricane, WV | 25° | 87° | 44" | 11" |
| Buena Vista, VA | 26° | 87° | 45" | 11" |
| Du Quoin, IL | 24° | 88° | 46" | 12" |
| Republic, MO | 23° | 88° | 45" | 14" |
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 Hartly averaged 1.9° warmer than the 1900s. The biggest change is in December (+3.4°).
A bigger shift than in 83% 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 Hartly compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Hartly’s place among Delaware’s.
Hartly weather by month
Highs, lows and precipitation from NOAA’s grid at Hartly’s center; snow, wet days and snow on the ground from Dover, DE. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 43° | 25° | 3.0" | 4.1" | 10 | 3 | 26° – 41° |
| February | 46° | 26° | 2.7" | 5.9" | 9 | 4 | 26° – 44° |
| March | 54° | 33° | 4.1" | 0.6" | 10 | 1 | 39° – 52° |
| April | 66° | 43° | 3.5" | 0.0" | 10 | 0 | 50° – 59° |
| May | 75° | 53° | 3.5" | 0.0" | 11 | 0 | 59° – 70° |
| June | 83° | 62° | 4.2" | 0.0" | 9 | 0 | 69° – 77° |
| July | 88° | 67° | 4.4" | 0.0" | 9 | 0 | 72° – 81° |
| August | 86° | 65° | 4.3" | 0.0" | 8 | 0 | 71° – 78° |
| September | 79° | 58° | 4.2" | 0.0" | 8 | 0 | 65° – 72° |
| October | 68° | 46° | 3.7" | 0.0" | 8 | 0 | 53° – 63° |
| November | 57° | 36° | 3.1" | 0.0" | 7 | 0 | 41° – 51° |
| December | 48° | 30° | 3.7" | 2.6" | 10 | 2 | 30° – 50° |
| Year | 66° | 45° | 44.4" | 13.2" | 110 | 9 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 30° to 50°. September is the most reliable, staying within 7°.
Where Hartly’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 Hartly’s center.
- Snow: Dover, DE.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Dover, DE, 11 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 Hartly’s climate
What is the weather like in Hartly?
A typical July afternoon reaches 88°, a January night drops to 25°, and about 13 inches of snow falls in a normal winter. Milder January nights than 63% of U.S. towns; hotter July afternoons than 65% of U.S. towns.
How cold does it get in Hartly in winter?
January nights average 25°. About 79 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 26°.
How much snow does Hartly get?
About 13 inches in a normal winter at Dover, DE, most of it in February, with snow on the ground about 9 days a year.
How hot does it get in Hartly?
July, with a typical high of 88° and a low of 67°. About 25 days a year reach 90° (Dover, DE).
When is the first and last frost in Hartly?
In half of years the last spring frost (32°) comes by April 4 and the first fall frost by November 4, about 214 frost-free days, at Dover, DE.
What growing zone is Hartly in?
Zone 7b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 6°.
What is the best time of year to visit Hartly?
By one simple rule (highs of 62–84° and lows of 40° or more), April, May, June, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Hartly getting warmer?
Yes: 1991–2020 averaged 1.9° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 83% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Hartly.
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.