Forest Grove, Oregon climate: Normal weather by month, frost dates and records
Forest Grove's normal year runs from 33°F December nights to 82°F August afternoons, with 46.7 inches of precipitation and 3 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 11.2°C, December lows of 0°C, August highs of 28°C, 1,187 mm of precipitation a year.
- NOAA stationForest Grove
- Station IDUSC00352997
- Location45.52°N 123.10°W
- Elevation180 ft (55 m)
- Population27,076
On October 23, the normal high in Forest Grove is 60°F and the normal low 40°F, and the chance of measurable rain or snow is 42%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Forest Grove.
- Jan 45° 33°
- Feb 49° 33°
- Mar 55° 36°
- Apr 60° 39°
- May 68° 45°
- Jun 73° 50°
- Jul 81° 54°
- Aug 82° 54°
- Sep 76° 49°
- Oct 63° 42°
- Nov 51° 36°
- Dec 44° 33°
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 Forest Grove each month?
August is the warmest month, with normal highs of 82°F; December the coldest, with normal lows of 33°F. The most precipitation falls in December (8.72 in), the least in July (0.32 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 45°F | 33°F | 38.8°F | 7.19 | 0.6 | 19 | <1 | 13 | 9 h |
| February | 49°F | 33°F | 41.2°F | 5.76 | 0.6 | 15 | <1 | 12 | 10 h 20 min |
| March | 55°F | 36°F | 45.2°F | 5.03 | 0.0 | 17 | <1 | 8 | 11 h 50 min |
| April | 60°F | 39°F | 49.6°F | 3.33 | 0.0 | 16 | <1 | 3 | 13 h 30 min |
| May | 68°F | 45°F | 56.7°F | 2.19 | 0.0 | 11 | 1 | <1 | 14 h 50 min |
| June | 73°F | 50°F | 61.4°F | 1.40 | 0.0 | 8 | 2 | <1 | 15 h 40 min |
| July | 81°F | 54°F | 67.6°F | 0.32 | 0.0 | 2 | 8 | <1 | 15 h 20 min |
| August | 82°F | 54°F | 67.9°F | 0.51 | 0.0 | 3 | 8 | <1 | 14 h 10 min |
| September | 76°F | 49°F | 62.4°F | 1.34 | 0.0 | 5 | 3 | <1 | 12 h 40 min |
| October | 63°F | 42°F | 52.4°F | 3.70 | 0.2 | 11 | <1 | 2 | 11 h |
| November | 51°F | 36°F | 43.6°F | 7.23 | 0.0 | 19 | <1 | 9 | 9 h 30 min |
| December | 44°F | 33°F | 38.4°F | 8.72 | 1.3 | 19 | <1 | 13 | 8 h 40 min |
| Year (annual) | 62°F | 42°F | 52.1°F | 46.72 | 2.7 | 146 | 23 | 61 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 7°C | 0°C | 3.8°C | 183 mm | 2 cm |
| February | 10°C | 1°C | 5.1°C | 146 mm | 2 cm |
| March | 13°C | 2°C | 7.3°C | 128 mm | 0 cm |
| April | 16°C | 4°C | 9.8°C | 85 mm | 0 cm |
| May | 20°C | 7°C | 13.7°C | 56 mm | 0 cm |
| June | 23°C | 10°C | 16.3°C | 36 mm | 0 cm |
| July | 27°C | 12°C | 19.8°C | 8 mm | 0 cm |
| August | 28°C | 12°C | 19.9°C | 13 mm | 0 cm |
| September | 24°C | 9°C | 16.9°C | 34 mm | 0 cm |
| October | 17°C | 5°C | 11.3°C | 94 mm | 1 cm |
| November | 11°C | 2°C | 6.4°C | 184 mm | 0 cm |
| December | 7°C | 0°C | 3.6°C | 221 mm | 3 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00352997; 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 Forest Grove?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, July has the fewest days with rain (2).
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 USC00352997.
When is the last frost in Forest Grove?
In Forest Grove, the last spring frost (32°F) comes after April 16 in half of years and after May 5 in one year in ten; the first autumn frost comes before October 26 in half of years and before October 6 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 161 year in 10 after May 5; 9 in 10 after March 26
- First autumn frost, half of years before
- October 261 year in 10 before October 6; 9 in 10 before November 14
NOAA puts the median frost-free season at 192 days, and the season without a hard freeze (28°F) at 236 days.
A hard freeze (28°F) comes after March 19 in half of springs and before November 11 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Forest Grove in zone 8b in ZIP code 97113, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Forest Grove's NOAA station is in zone 8a: the coldest night of a typical year reaches 14°F (19 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 Oregon · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00352997; 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 Forest Grove?
In a normal year in Forest Grove, 23 days a year reach 90°F (2 of them 100°F or more), 61 nights fall to 32°F or colder and 146 days bring measurable precipitation.
- Days at 90°F or more
- 23a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 61a normal year
- Days that stay below freezing
- 2high of 32°F or less
- Days with 0.01 inch of precipitation
- 146a normal year
- Days with 1 inch of snow or more
- 1a normal year
The highest temperature in this station's record (since 1893) is 113°F, on June 29, 2021; the lowest is −12°F, on February 3, 1950.
The wettest calendar year on that record is 1998, with 63.31 in; the snowiest season is 1949–50, with 60.8 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00352997; records: ACIS (NOAA Regional Climate Centers), station USC00352997. Records use complete months only; a month missing more than three days is left out.
How sunny is Forest Grove?
Over a year 70% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Forest Grove, 3.7 kWh per square metre a day. July is the sunniest month (83%) and December the cloudiest (52%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 54% | 1.2 |
| February | 60% | 2.1 |
| March | 59% | 3.0 |
| April | 63% | 4.3 |
| May | 68% | 5.4 |
| June | 70% | 6.0 |
| July | 83% | 6.8 |
| August | 83% | 5.8 |
| September | 78% | 4.3 |
| October | 67% | 2.6 |
| November | 56% | 1.4 |
| December | 52% | 1.0 |
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 Forest Grove need?
A normal year in Forest Grove brings 5,027 heating degree days, 6% fewer than the median U.S. place (5,373), and 347 cooling degree days, 62% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,256 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 812 | 0 |
| February | 665 | 0 |
| March | 612 | 0 |
| April | 461 | 1 |
| May | 273 | 16 |
| June | 147 | 39 |
| July | 42 | 122 |
| August | 35 | 123 |
| September | 123 | 45 |
| October | 391 | 2 |
| November | 642 | 0 |
| December | 825 | 0 |
| Year (annual) | 5,027 | 347 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00352997. 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 Forest Grove been warmer than normal lately?
2025 averaged 54.5°F, 2.4°F above the 1991-2020 normal of 52.1°F. 4 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 53.0°F | +0.9°F | 40.11 | – |
| 2022 | 52.5°F | +0.4°F | 41.24 | 0.0 |
| 2024 | 54.2°F | +2.1°F | – | 1.5 |
| 2025 | 54.5°F | +2.4°F | – | – |
Over 82 complete years from 1892 to 2025, the station's annual mean temperature rose at a fitted 2.2°F per century (+0.12°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00352997; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Forest Grove's climate compare?
Forest Grove is warmer than 54 of the other 104 places with their own NOAA record in Oregon, and wetter than 63. Across the 7,247 U.S. stations with normals, its annual mean of 52.1°F is warmer than 50%.
In the Köppen classification computed from these normals, Forest Grove is Csb: temperate, dry-summer, warm 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 Forest Grove share this climate record?
5 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.
- Cornelius, OR15,369 people · 3 mi E
- Banks, OR1,831 people · 6 mi N
- Gaston, OR676 people · 7 mi S
- Cherry Grove, OR365 people · 9 mi SW
- Dilley, OR206 people · 2 mi SW
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 Forest Grove's climate
What is the coldest month in Forest Grove?
December, with a normal high of 44°F and a normal low of 33°F. The warmest is August (82°F by day, 54°F at night).
Does it snow in Forest Grove?
Yes: 3 inches in a normal year, falling on 1 days with 0.1 inch or more, the most in December (1.3 inches).
What is the rainiest month in Forest Grove?
December, with 8.72 in of precipitation in a normal year; the driest is July with 0.32 in.
What plant hardiness zone is Forest Grove in?
The USDA's 2023 map puts Forest Grove in zone 8b in ZIP code 97113, the nearest ZIP area. By the same method at Forest Grove's NOAA station, the coldest night of a typical year reaches 14°F (19 years, 1991-2020): zone 8a.
How late can frost come in Forest Grove?
In half of years the last 32°F night comes after April 16; in one year in ten it comes after May 5. Waiting until May 5 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Oregon climateThe statewide normals and every place in the state
- Hillsboro, OR7 miles from this station, 52.5°F a year
- Nature Park-Beaverton, OR13 miles from this station, 55.8°F a year
- Beaverton, OR14 miles from this station, 53.7°F a year
- Rex (1 mi S), OR18 miles from this station, 53.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made