Riverhead, New York climate: Normal weather by month, frost dates and records
Riverhead's normal year runs from 26°F January nights to 84°F July afternoons, with 47.2 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.2°C, January lows of −3°C, July highs of 29°C, 1,199 mm of precipitation a year.
- NOAA stationRiverhead Research Farm
- Station IDUSC00307134
- Location40.96°N 72.72°W
- Elevation100 ft (31 m)
- Population (census place)15,073
On October 14, the normal high in Riverhead is 66°F and the normal low 50°F, and the chance of measurable rain or snow is 29%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Riverhead.
- Jan 40° 26°
- Feb 41° 27°
- Mar 48° 33°
- Apr 60° 42°
- May 70° 51°
- Jun 79° 61°
- Jul 84° 67°
- Aug 82° 66°
- Sep 76° 60°
- Oct 65° 50°
- Nov 54° 40°
- Dec 45° 32°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Riverhead each month?
July is the warmest month, with normal highs of 84°F; January the coldest, with normal lows of 26°F. The most precipitation falls in March (4.72 in), the least in July (3.05 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 40°F | 26°F | 32.9°F | 3.79 | 10 | <1 | 24 | 9 h 30 min |
| February | 41°F | 27°F | 34.1°F | 3.31 | 8 | <1 | 21 | 10 h 40 min |
| March | 48°F | 33°F | 40.5°F | 4.72 | 10 | <1 | 16 | 11 h 50 min |
| April | 60°F | 42°F | 50.7°F | 4.08 | 11 | <1 | 2 | 13 h 20 min |
| May | 70°F | 51°F | 60.6°F | 3.60 | 11 | 1 | <1 | 14 h 30 min |
| June | 79°F | 61°F | 69.6°F | 3.82 | 9 | 2 | <1 | 15 h 10 min |
| July | 84°F | 67°F | 75.4°F | 3.05 | 8 | 5 | <1 | 14 h 50 min |
| August | 82°F | 66°F | 74.2°F | 3.93 | 8 | 2 | <1 | 13 h 50 min |
| September | 76°F | 60°F | 68.0°F | 4.07 | 8 | <1 | <1 | 12 h 30 min |
| October | 65°F | 50°F | 57.2°F | 4.46 | 9 | <1 | <1 | 11 h 10 min |
| November | 54°F | 40°F | 47.0°F | 3.81 | 9 | <1 | 6 | 10 h |
| December | 45°F | 32°F | 38.4°F | 4.58 | 11 | <1 | 17 | 9 h 20 min |
| Year (annual) | 62°F | 46°F | 54.0°F | 47.22 | 111 | 10 | 86 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 4°C | −3°C | 0.5°C | 96 mm |
| February | 5°C | −3°C | 1.2°C | 84 mm |
| March | 9°C | 0°C | 4.7°C | 120 mm |
| April | 15°C | 5°C | 10.4°C | 104 mm |
| May | 21°C | 11°C | 15.9°C | 91 mm |
| June | 26°C | 16°C | 20.9°C | 97 mm |
| July | 29°C | 19°C | 24.1°C | 77 mm |
| August | 28°C | 19°C | 23.4°C | 100 mm |
| September | 24°C | 16°C | 20.0°C | 103 mm |
| October | 18°C | 10°C | 14.0°C | 113 mm |
| November | 12°C | 4°C | 8.3°C | 97 mm |
| December | 7°C | 0°C | 3.6°C | 116 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Bridgehampton (22 miles away), gets 27 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00307134; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Riverhead?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, September has the fewest days with rain (8).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00307134.
When is the last frost in Riverhead?
In Riverhead, the last spring frost (32°F) comes after April 6 in half of years and after April 19 in one year in ten; the first autumn frost comes before November 9 in half of years and before October 28 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 61 year in 10 after April 19; 9 in 10 after March 27
- First autumn frost, half of years before
- November 91 year in 10 before October 28; 9 in 10 before November 22
NOAA puts the median frost-free season at 215 days, and the season without a hard freeze (28°F) at 239 days.
A hard freeze (28°F) comes after March 28 in half of springs and before November 21 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Riverhead in zone 7a in ZIP code 11901. By the map's own method, the average of each year's coldest night over 1991-2020, Riverhead's NOAA station is in zone 7b: the coldest night of a typical year reaches 7°F (29 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in New York · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00307134; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Riverhead?
In a normal year in Riverhead, 10 days a year reach 90°F, 86 nights fall to 32°F or colder and 111 days bring measurable precipitation.
- Days at 90°F or more
- 10a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 86a normal year
- Days that stay below freezing
- 14high of 32°F or less
- Days with 0.01 inch of precipitation
- 111a normal year
The highest temperature in this station's record (since 1938) is 100°F, on July 21, 1991; the lowest is −8°F, on January 18, 1982.
The wettest calendar year on that record is 1989, with 62.25 in; the snowiest season is 1995–96, with 78.8 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00307134; records: ACIS (NOAA Regional Climate Centers), station USC00307134. Records use complete months only; a month missing more than three days is left out.
How sunny is Riverhead?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Riverhead, 4.0 kWh per square metre a day. August is the sunniest month (82%) and December the cloudiest (64%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 65% | 1.8 |
| February | 69% | 2.7 |
| March | 71% | 3.8 |
| April | 73% | 5.0 |
| May | 73% | 5.6 |
| June | 77% | 6.1 |
| July | 82% | 6.1 |
| August | 82% | 5.5 |
| September | 79% | 4.4 |
| October | 72% | 3.0 |
| November | 70% | 2.1 |
| December | 64% | 1.5 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Riverhead need?
A normal year in Riverhead brings 4,906 heating degree days, 9% fewer than the median U.S. place (5,373), and 945 cooling degree days, 4% more than the median (908). Six months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,416 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 997 | 0 |
| February | 865 | 0 |
| March | 760 | 0 |
| April | 434 | 3 |
| May | 169 | 33 |
| June | 23 | 161 |
| July | 0 | 323 |
| August | 1 | 286 |
| September | 36 | 125 |
| October | 257 | 15 |
| November | 540 | 0 |
| December | 825 | 0 |
| Year (annual) | 4,906 | 945 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00307134. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Riverhead been warmer than normal lately?
2025 averaged 54.5°F, 0.5°F above the 1991-2020 normal of 54.0°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 55.4°F | +1.4°F | 45.03 |
| 2022 | 55.1°F | +1.1°F | 45.40 |
| 2023 | 56.0°F | +2.0°F | 48.70 |
| 2024 | 55.9°F | +1.9°F | 52.92 |
| 2025 | 54.5°F | +0.5°F | 38.06 |
Over 69 complete years from 1942 to 2025, the station's annual mean temperature rose at a fitted 2.4°F per century (+0.13°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00307134; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Riverhead's climate compare?
Riverhead is warmer than 126 of the other 130 places with their own NOAA record in New York, and wetter than 88. Across the 7,247 U.S. stations with normals, its annual mean of 54.0°F is warmer than 57%.
In the Köppen classification computed from these normals, Riverhead is Cfa: temperate, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Riverhead share this climate record?
2 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Aquebogue, NY1,778 people · 5 mi E
- Northville, NY1,771 people · 5 mi E
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Riverhead's climate
What is the coldest month in Riverhead?
January, with a normal high of 40°F and a normal low of 26°F. The warmest is July (84°F by day, 67°F at night).
Does it snow in Riverhead?
Yes. NOAA publishes no 1991-2020 snowfall normal for Riverhead's NOAA station; the nearest record that keeps one, Bridgehampton (22 miles away), records 27 inches of snow in a normal year.
What is the rainiest month in Riverhead?
March, with 4.72 in of precipitation in a normal year; the driest is July with 3.05 in.
What plant hardiness zone is Riverhead in?
The USDA's 2023 map puts Riverhead in zone 7a in ZIP code 11901. By the same method at Riverhead's NOAA station, the coldest night of a typical year reaches 7°F (29 years, 1991-2020): zone 7b.
How late can frost come in Riverhead?
In half of years the last 32°F night comes after April 6; in one year in ten it comes after April 19. Waiting until April 19 leaves about a one-in-ten chance of a later frost.
Nearby and next
- New York climateThe statewide normals and every place in the state
- Baiting Hollow, NY2 miles from this station, 51.1°F a year
- Westhamptn Gabreski Airport, NY9 miles from this station, 50.2°F a year
- Upton Cooperative - Weather Office New York, NY10 miles from this station, 51.2°F a year
- Mattituck, NY11 miles from this station, 51.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made