Photo: Jerrye & Roy Klotz, MD · CC BY-SA 3.0Riverdale’s winters are colder and snowier than most of the U.S.
A typical July afternoon reaches 86°, a January night drops to 21°, and about 28 inches of snow falls in a normal winter.
A year in Riverdale at a glance
Each month’s typical high and low, and what it brings.
What stands out about Riverdale’s climate
Compared with towns across the U.S., with Riverdale’s place in New Jersey beside it.
What a year in Riverdale feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 174 frost-free days a year
In half of years the last 32° night comes by April 25 and the first by October 17. Frost and day counts come from NOAA’s station at Charlotteburg Reservoir, NJ, 6 miles from the town’s center, 470 ft higher.
The 2023 USDA map puts Riverdale’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 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 48 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 Riverdale
91% 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 Charlotteburg Reservoir, NJ.
Living with Riverdale’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
174 frost-free days in zone 7a. 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 17.
Months with highs of 62–84° and lows of 40° or more: May, June, August, September and October. 0.5 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Riverdale from natural hazards, river flooding is the largest share (86%); heat waves, cold waves, winter storms and ice storms together are 6%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Riverdale and its neighbors
Kinnelon 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.
Climates most like Riverdale’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 |
|---|---|---|---|---|
| Riverdale, NJ | 21° | 86° | 48" | 28" |
| New Martinsville, WV | 22° | 85° | 46" | 27" |
| New Freedom, PA | 21° | 84° | 48" | 29" |
| Westminster, MD | 22° | 86° | 45" | 28" |
| Elsmere, KY | 23° | 85° | 47" | 23" |
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 Riverdale averaged 2.1° warmer than the 1900s. The biggest change is in December (+3.5°).
A bigger shift than in 93% 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 Riverdale compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Riverdale’s place among New Jersey’s.
Riverdale weather by month
Highs, lows and precipitation from NOAA’s grid at Riverdale’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 | 38° | 21° | 3.4" | 9.6" | 11 | 21° – 36° |
| February | 41° | 22° | 2.7" | 7.7" | 9 | 19° – 38° |
| March | 49° | 29° | 3.9" | 5.3" | 11 | 33° – 49° |
| April | 62° | 39° | 3.9" | 1.4" | 10 | 46° – 55° |
| May | 72° | 49° | 4.0" | 0.0" | 11 | 56° – 66° |
| June | 81° | 58° | 4.6" | 0.0" | 11 | 67° – 72° |
| July | 86° | 64° | 4.4" | 0.0" | 9 | 70° – 79° |
| August | 84° | 62° | 4.5" | 0.0" | 9 | 69° – 76° |
| September | 77° | 55° | 4.5" | 0.0" | 8 | 63° – 70° |
| October | 65° | 43° | 4.5" | 0.0" | 8 | 50° – 60° |
| November | 53° | 34° | 3.6" | 0.2" | 8 | 39° – 48° |
| December | 43° | 26° | 4.2" | 3.9" | 11 | 28° – 45° |
| Year | 63° | 42° | 48.1" | 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 19° to 38°. June is the most reliable, staying within 6°.
Where Riverdale’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 Riverdale’s center.
- Snow: Oak Ridge Reservoir, NJ.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Charlotteburg Reservoir, NJ, 6 miles from the town’s center, 470 ft higher; 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 Riverdale’s climate
What is the weather like in Riverdale?
A typical July afternoon reaches 86°, a January night drops to 21°, and about 28 inches of snow falls in a normal winter. Colder January nights than 56% of U.S. towns; hotter July afternoons than 53% of U.S. towns.
How cold does it get in Riverdale in winter?
January nights average 21°. About 138 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 21°.
How much snow does Riverdale get?
About 28 inches in a normal winter at Oak Ridge Reservoir, NJ, most of it in January.
How hot does it get in Riverdale?
July, with a typical high of 86° and a low of 64°. About 10 days a year reach 90° (Charlotteburg Reservoir, NJ).
When is the first and last frost in Riverdale?
In half of years the last spring frost (32°) comes by April 25 and the first fall frost by October 17, about 174 frost-free days, at Charlotteburg Reservoir, NJ.
What growing zone is Riverdale 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 Riverdale?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Riverdale getting warmer?
Yes: 1991–2020 averaged 2.1° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 93% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Riverdale.
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.