St. Helens, Oregon climate: Normal weather by month, frost dates and records
St. Helens's normal year runs from 33°F December nights to 79°F August afternoons. (NOAA 1991-2020 normals)
In metric: a yearly mean of 10.9°C, December lows of 1°C, August highs of 26°C.
- NOAA stationSaint Helens Rfd
- Station IDUSC00357466
- Location45.85°N 122.87°W
- Elevation269 ft (82 m)
- Population14,460
On October 14, the normal high in St. Helens is 61°F and the normal low 45°F.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for St. Helens.
- Jan 43° 33°
- Feb 47° 33°
- Mar 53° 36°
- Apr 59° 40°
- May 67° 46°
- Jun 72° 50°
- Jul 79° 55°
- Aug 79° 55°
- Sep 74° 52°
- Oct 61° 45°
- Nov 49° 38°
- Dec 42° 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 St. Helens each month?
August is the warmest month, with normal highs of 79°F; December the coldest, with normal lows of 33°F.
| Month | High | Low | Mean | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|
| January | 43°F | 33°F | 38.0°F | – | <1 | 14 | 9 h |
| February | 47°F | 33°F | 40.2°F | – | <1 | 12 | 10 h 20 min |
| March | 53°F | 36°F | 44.5°F | – | <1 | 8 | 11 h 50 min |
| April | 59°F | 40°F | 49.4°F | – | <1 | 3 | 13 h 30 min |
| May | 67°F | 46°F | 56.3°F | – | 1 | 1 | 14 h 50 min |
| June | 72°F | 50°F | 61.0°F | – | 2 | <1 | 15 h 40 min |
| July | 79°F | 55°F | 66.9°F | – | 7 | <1 | 15 h 20 min |
| August | 79°F | 55°F | 67.1°F | – | 7 | <1 | 14 h 10 min |
| September | 74°F | 52°F | 62.7°F | – | 3 | <1 | 12 h 40 min |
| October | 61°F | 45°F | 52.6°F | – | <1 | 1 | 11 h |
| November | 49°F | 38°F | 43.3°F | – | <1 | 8 | 9 h 30 min |
| December | 42°F | 33°F | 37.6°F | – | <1 | 12 | 8 h 40 min |
| Year (annual) | 60°F | 43°F | 51.6°F | – | 20 | 59 |
The same normals in °C and millimetres
| Month | High | Low | Mean |
|---|---|---|---|
| January | 6°C | 0°C | 3.3°C |
| February | 8°C | 1°C | 4.6°C |
| March | 12°C | 2°C | 6.9°C |
| April | 15°C | 5°C | 9.7°C |
| May | 19°C | 8°C | 13.5°C |
| June | 22°C | 10°C | 16.1°C |
| July | 26°C | 13°C | 19.4°C |
| August | 26°C | 13°C | 19.5°C |
| September | 23°C | 11°C | 17.1°C |
| October | 16°C | 7°C | 11.4°C |
| November | 9°C | 3°C | 6.3°C |
| December | 6°C | 1°C | 3.1°C |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Vernonia (15 miles away), gets 1 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00357466; 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 St. Helens?
Normal highs sit between 65°F and 85°F in May, June, July, August and September.
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 USC00357466.
When is the last frost in St. Helens?
In St. Helens, the last spring frost (32°F) comes after April 18 in half of years and after May 26 in one year in ten; the first autumn frost comes before November 7 in half of years and before October 21 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 181 year in 10 after May 26; 9 in 10 after March 20
- First autumn frost, half of years before
- November 71 year in 10 before October 21; 9 in 10 before November 26
NOAA puts the median frost-free season at 201 days, and the season without a hard freeze (28°F) at 244 days.
A hard freeze (28°F) comes after March 24 in half of springs and before November 24 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts St. Helens in zone 8b in ZIP code 97018, the nearest ZIP area.
Frost dates for every NOAA station in Oregon · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00357466; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. 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 St. Helens?
In a normal year in St. Helens, 20 days a year reach 90°F (2 of them 100°F or more) and 59 nights fall to 32°F or colder.
- Days at 90°F or more
- 20a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 59a normal year
- Days that stay below freezing
- 2high of 32°F or less
Source: NOAA NCEI 1991-2020 annual normals, station USC00357466.
How sunny is St. Helens?
Over a year 70% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around St. Helens, 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 St. Helens need?
A normal year in St. Helens brings 5,158 heating degree days, 4% fewer than the median U.S. place (5,373), and 305 cooling degree days, 66% 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 2,198 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 835 | 0 |
| February | 696 | 0 |
| March | 636 | 0 |
| April | 469 | 1 |
| May | 281 | 12 |
| June | 151 | 31 |
| July | 49 | 107 |
| August | 42 | 107 |
| September | 115 | 46 |
| October | 386 | 1 |
| November | 650 | 0 |
| December | 851 | 0 |
| Year (annual) | 5,158 | 305 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00357466. 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 St. Helens's climate compare?
St. Helens is warmer than 48 of the other 104 places with their own NOAA record in Oregon. Across the 7,247 U.S. stations with normals, its annual mean of 51.6°F is warmer than 48%.
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers.
Which places near St. Helens share this climate record?
7 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.
- Woodland, WA6,496 people · 7 mi NE
- La Center, WA4,256 people · 10 mi E
- Kalama, WA3,131 people · 12 mi N
- Columbia City, OR1,949 people · 5 mi NE
- Amboy, WA1,545 people · 19 mi E
- Warren, OR1,459 people · 2 mi S
- Deer Island, OR191 people · 6 mi N
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 St. Helens's climate
What is the coldest month in St. Helens?
December, with a normal high of 42°F and a normal low of 33°F. The warmest is August (79°F by day, 55°F at night).
Does it snow in St. Helens?
Yes. NOAA publishes no 1991-2020 snowfall normal for St. Helens's NOAA station; the nearest record that keeps one, Vernonia (15 miles away), records 1 inches of snow in a normal year.
What plant hardiness zone is St. Helens in?
The USDA's 2023 map puts St. Helens in zone 8b in ZIP code 97018, the nearest ZIP area.
How late can frost come in St. Helens?
In half of years the last 32°F night comes after April 18; in one year in ten it comes after May 26. Waiting until May 26 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Oregon climateThe statewide normals and every place in the state
- Scappoose, OR6 miles from this station, 53.0°F a year
- Vernonia, OR16 miles from this station, 49.4°F a year
- Hazel Dell, WA16 miles from this station, 51.0°F a year
- Battle Ground, WA17 miles from this station, 50.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made