Lake Hopatcong gets more rain and snow than 85% of U.S. towns: 50 inches of precipitation a year
January mornings start at about 18°. In July, afternoons here are cooler than in 81% of U.S. towns. Since 1901–2000, the year has warmed by 1.9°, most of all in December. Plan time outside from May to October, when highs sit at 62–82°.
A year in Lake Hopatcong at a glance
Each month’s typical high and low, and what it brings.
What stands out about Lake Hopatcong’s climate
Compared with towns across the U.S., with Lake Hopatcong’s place in New Jersey beside it.
What a year in Lake Hopatcong 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 25 and the first by October 19. Frost and day counts come from NOAA’s station at Andover Aeroflex Airport, 7 miles from the town’s center, 380 ft lower.
The 2023 USDA map puts Lake Hopatcong’s center in zone 6b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −3°. 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 28 inches of snow a winter
Snow, measured at Oak Ridge Reservoir, NJ, falls mostly in January. Precipitation (rain plus melted snow) adds up to 50 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 115 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Lake Hopatcong
90% 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 Andover Aeroflex Airport.
Living with Lake Hopatcong’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 25 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 19.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 9.6 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Lake Hopatcong from natural hazards, river flooding is the largest share (61%); heat waves, cold waves, winter storms and ice storms together are 19%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Lake Hopatcong and its neighbors
Lower Berkshire Valley the hottest July afternoons (83°, 1° warmer). Differences under a degree are within what the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Lake Hopatcong’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 |
|---|---|---|---|---|
| Lake Hopatcong, NJ | 18° | 82° | 50" | 28" |
| West Greenwich, RI | 20° | 82° | 51" | 35" |
| Carver, MA | 21° | 83° | 51" | 31" |
| Putnam, CT | 18° | 82° | 50" | 39" |
| Punxsutawney, PA | 17° | 82° | 45" | 35" |
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 Lake Hopatcong averaged 1.9° warmer than the 1900s. The biggest change is in December (+3.5°).
A bigger shift than in 85% 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 Lake Hopatcong compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Lake Hopatcong’s place among New Jersey’s.
Lake Hopatcong weather by month
Highs, lows and precipitation from NOAA’s grid at Lake Hopatcong’s center; snow, wet days and snow on the ground from Oak Ridge Reservoir, NJ. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 35° | 18° | 3.7" | 9.6" | 11 | 18° – 34° |
| February | 38° | 20° | 2.9" | 7.7" | 9 | 16° – 35° |
| March | 47° | 27° | 4.2" | 5.3" | 11 | 30° – 46° |
| April | 59° | 37° | 4.1" | 1.4" | 10 | 44° – 53° |
| May | 69° | 47° | 4.1" | 0.0" | 11 | 53° – 63° |
| June | 78° | 55° | 4.8" | 0.0" | 11 | 63° – 69° |
| July | 82° | 61° | 4.7" | 0.0" | 9 | 67° – 75° |
| August | 81° | 59° | 4.5" | 0.0" | 9 | 66° – 73° |
| September | 74° | 52° | 4.6" | 0.0" | 8 | 60° – 67° |
| October | 62° | 41° | 4.7" | 0.0" | 8 | 47° – 59° |
| November | 50° | 32° | 3.6" | 0.2" | 8 | 37° – 46° |
| December | 40° | 24° | 4.5" | 3.9" | 11 | 25° – 42° |
| Year | 60° | 39° | 50.4" | 28.1" | 115 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 16° to 35°. June is the most reliable, staying within 6°.
Where Lake Hopatcong’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 Lake Hopatcong’s center.
- Snow: Oak Ridge Reservoir, NJ.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Andover Aeroflex Airport, 7 miles from the town’s center, 380 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 Lake Hopatcong’s climate
What is the weather like in Lake Hopatcong?
A typical July afternoon reaches 82°, a January night drops to 18°, and about 28 inches of snow falls in a normal winter. Colder January nights than 69% of U.S. towns; cooler July afternoons than 81% of U.S. towns.
How cold does it get in Lake Hopatcong in winter?
January nights average 18°. About 127 nights a year reach 32° or below and 3 reach 0° or below. In the coldest January of the last 30 years the month averaged 18°.
How much snow does Lake Hopatcong get?
About 28 inches in a normal winter at Oak Ridge Reservoir, NJ, most of it in January.
How hot does it get in Lake Hopatcong?
July, with a typical high of 82° and a low of 61°. About 11 days a year reach 90° (Andover Aeroflex Airport).
When is the first and last frost in Lake Hopatcong?
In half of years the last spring frost (32°) comes by April 25 and the first fall frost by October 19, about 175 frost-free days, at Andover Aeroflex Airport.
What growing zone is Lake Hopatcong in?
Zone 6b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −3°.
What is the best time of year to visit Lake Hopatcong?
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 Lake Hopatcong getting warmer?
Yes: 1991–2020 averaged 1.9° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 85% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Lake Hopatcong.
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.