Prospect, Oregon climate: Normal weather by month, frost dates and records
Prospect's normal year runs from 30°F December nights to 89°F July afternoons, with 41.3 inches of precipitation and 21 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 11.5°C, December lows of −1°C, July highs of 32°C, 1,049 mm of precipitation a year.
- NOAA stationProspect (2 mi SW)
- Station IDUSC00356907
- Location42.73°N 122.52°W
- Elevation2,482 ft (757 m)
- Population (census place)724
On October 23, the normal high in Prospect is 67°F and the normal low 36°F, and the chance of measurable rain or snow is 35%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Prospect.
- Jan 50° 30°
- Feb 54° 31°
- Mar 58° 33°
- Apr 62° 35°
- May 71° 41°
- Jun 78° 45°
- Jul 89° 50°
- Aug 89° 49°
- Sep 84° 44°
- Oct 70° 38°
- Nov 55° 34°
- Dec 48° 30°
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 Prospect each month?
July is the warmest month, with normal highs of 89°F; December the coldest, with normal lows of 30°F. The most precipitation falls in December (7.20 in), the least in August (0.47 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 50°F | 30°F | 40.1°F | 5.97 | 7.6 | 16 | <1 | 21 | 9 h 20 min |
| February | 54°F | 31°F | 42.2°F | 4.42 | 3.1 | 14 | <1 | 18 | 10 h 30 min |
| March | 58°F | 33°F | 45.2°F | 4.38 | 2.3 | 16 | <1 | 18 | 11 h 50 min |
| April | 62°F | 35°F | 48.7°F | 3.71 | 1.0 | 15 | <1 | 11 | 13 h 20 min |
| May | 71°F | 41°F | 55.9°F | 2.59 | 0.0 | 11 | 1 | 4 | 14 h 40 min |
| June | 78°F | 45°F | 61.5°F | 1.27 | 0.0 | 5 | 3 | 1 | 15 h 20 min |
| July | 89°F | 50°F | 69.5°F | 0.57 | 0.0 | 2 | 14 | <1 | 15 h |
| August | 89°F | 49°F | 69.3°F | 0.47 | 0.0 | 2 | 15 | <1 | 14 h |
| September | 84°F | 44°F | 63.6°F | 1.16 | 0.0 | 4 | 9 | 1 | 12 h 30 min |
| October | 70°F | 38°F | 54.0°F | 3.25 | 0.0 | 9 | 1 | 7 | 11 h 10 min |
| November | 55°F | 34°F | 44.1°F | 6.31 | 2.9 | 17 | <1 | 14 | 9 h 50 min |
| December | 48°F | 30°F | 38.8°F | 7.20 | 4.0 | 17 | <1 | 21 | 9 h |
| Year (annual) | 67°F | 38°F | 52.7°F | 41.30 | 20.9 | 129 | 43 | 116 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 10°C | −1°C | 4.5°C | 152 mm | 19 cm |
| February | 12°C | −1°C | 5.7°C | 112 mm | 8 cm |
| March | 14°C | 0°C | 7.3°C | 111 mm | 6 cm |
| April | 17°C | 2°C | 9.3°C | 94 mm | 3 cm |
| May | 22°C | 5°C | 13.3°C | 66 mm | 0 cm |
| June | 26°C | 7°C | 16.4°C | 32 mm | 0 cm |
| July | 32°C | 10°C | 20.8°C | 14 mm | 0 cm |
| August | 32°C | 10°C | 20.7°C | 12 mm | 0 cm |
| September | 29°C | 7°C | 17.6°C | 29 mm | 0 cm |
| October | 21°C | 3°C | 12.2°C | 83 mm | 0 cm |
| November | 13°C | 1°C | 6.7°C | 160 mm | 7 cm |
| December | 9°C | −1°C | 3.8°C | 183 mm | 10 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00356907; 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 Prospect?
Normal highs sit between 65°F and 85°F in May, June, September and October. Of those, September has the fewest days with rain (4).
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 USC00356907.
When is the last frost in Prospect?
In Prospect, the last spring frost (32°F) comes after May 19 in half of years and after June 9 in one year in ten; the first autumn frost comes before October 3 in half of years and before September 13 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
- May 191 year in 10 after June 9; 9 in 10 after April 29
- First autumn frost, half of years before
- October 31 year in 10 before September 13; 9 in 10 before October 20
NOAA puts the median frost-free season at 136 days, and the season without a hard freeze (28°F) at 182 days.
A hard freeze (28°F) comes after April 26 in half of springs and before October 24 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Prospect in zone 8a in ZIP code 97536, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Prospect's NOAA station is in zone 8a: the coldest night of a typical year reaches 15°F (15 complete years).
Frost dates for every NOAA station in Oregon · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00356907; 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 Prospect?
In a normal year in Prospect, 43 days a year reach 90°F (5 of them 100°F or more), 116 nights fall to 32°F or colder and 129 days bring measurable precipitation.
- Days at 90°F or more
- 43a normal year
- Days at 100°F or more
- 5a normal year
- Nights at 32°F or colder
- 116a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 129a normal year
- Days with 1 inch of snow or more
- 8a normal year
The highest temperature in this station's record (since 1905) is 110°F, on August 8, 1981; the lowest is −12°F, on January 8, 1937.
The wettest calendar year on that record is 1996, with 66.55 in; the snowiest season is 1936–37, with 146.4 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00356907; records: ACIS (NOAA Regional Climate Centers), station USC00356907. Records use complete months only; a month missing more than three days is left out.
How sunny is Prospect?
Over a year 80% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Prospect, 4.5 kWh per square metre a day. July is the sunniest month (94%) and December the cloudiest (59%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 63% | 1.7 |
| February | 67% | 2.6 |
| March | 67% | 3.7 |
| April | 71% | 5.2 |
| May | 78% | 6.5 |
| June | 86% | 7.6 |
| July | 94% | 8.0 |
| August | 93% | 6.9 |
| September | 89% | 5.3 |
| October | 80% | 3.5 |
| November | 66% | 2.0 |
| December | 59% | 1.4 |
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 Prospect need?
A normal year in Prospect brings 4,888 heating degree days, 9% fewer than the median U.S. place (5,373), and 434 cooling degree days, 52% 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 2,429 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 772 | 0 |
| February | 638 | 0 |
| March | 612 | 0 |
| April | 489 | 0 |
| May | 294 | 11 |
| June | 144 | 39 |
| July | 23 | 163 |
| August | 22 | 154 |
| September | 104 | 62 |
| October | 348 | 5 |
| November | 627 | 0 |
| December | 814 | 0 |
| Year (annual) | 4,888 | 434 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00356907. 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.
How does Prospect's climate compare?
Prospect is warmer than 63 of the other 104 places with their own NOAA record in Oregon, and wetter than 56. Across the 7,247 U.S. stations with normals, its annual mean of 52.7°F is warmer than 52%.
In the Köppen classification computed from these normals, Prospect 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.
Questions about Prospect's climate
What is the coldest month in Prospect?
December, with a normal high of 48°F and a normal low of 30°F. The warmest is July (89°F by day, 50°F at night).
Does it snow in Prospect?
Yes: 21 inches in a normal year, falling on 9 days with 0.1 inch or more, the most in January (7.6 inches).
What is the rainiest month in Prospect?
December, with 7.20 in of precipitation in a normal year; the driest is August with 0.47 in.
What plant hardiness zone is Prospect in?
The USDA's 2023 map puts Prospect in zone 8a in ZIP code 97536, the nearest ZIP area. By the same method at Prospect's NOAA station, the coldest night of a typical year reaches 15°F (15 years, 1991-2020): zone 8a.
How late can frost come in Prospect?
In half of years the last 32°F night comes after May 19; in one year in ten it comes after June 9. Waiting until June 9 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Oregon climateThe statewide normals and every place in the state
- Lost Creek Dam, OR9 miles from this station, 53.6°F a year
- Crater Lake NPS Headquarters, OR22 miles from this station, 37.9°F a year
- Chiloquin 12 NW (Fort Klamath), OR27 miles from this station, 45.0°F a year
- Medford, OR30 miles from this station, 55.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made