USDA Hardiness Zone 8b
Frost Dates for 97051 — Saint Helens, Oregon
NOAA 1991–2020 normals from Saint Helens Rfd, OR (269 ft), 2 miles southwest.
Updated
In Saint Helens, the last spring frost (32°F) is around April 18 in half of years and has passed by May 26 in nine years out of ten. The first fall frost comes around November 7, as early as October 21 one year in ten, leaving a typical freeze-free season of 201 days (NOAA, Saint Helens Rfd, OR).
- Last spring frost
- April 18
- First fall frost
- November 7
- Growing season
- 201 days
- Hardiness zone
- 8b
50% probability
50% probability
freeze-free, 50%
15 to 20°F (-9.4 to -6.7°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 20%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
4 of 20 observed
NOAA normal
Frost risk by date in Saint Helens
Half of springs at Saint Helens Rfd, OR see their last 32°F night by April 18; only one in ten is past it by March 20, and one in ten still has one after May 26. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 9 20%, and after May 26 10%. The 38 days between the even-odds date and the one-in-ten date is wider than at 98% of the 103 Oregon stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.
In fall the first 32°F night comes by November 7 in half of years, as early as October 21 one year in ten, and holds off past November 26 one year in ten. A hard freeze of 28°F follows 17 days later, around November 24; in spring the one-in-ten date for 28°F is May 6, 20 days before the 32°F one. The freeze-free season lasts 201 days in a typical year, longer than at 51% of the 103 Oregon stations; it reaches 235 days one year in ten and falls short of 164 one year in ten. On average 59 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 18 days longer, to about May 6, and return around October 24. Nights of 24°F, cold enough to damage hardier plants, come in 98% of winters and 16°F in 39%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 18 | Apr 25 | Apr 29 | May 2 | May 6 | May 12 | May 19 | May 29 | Jun 9 |
| 32°F | Mar 20 | Mar 30 | Apr 4 | Apr 12 | Apr 18 | Apr 25 | Apr 30 | May 9 | May 26 |
| 28°F | Feb 20 | Feb 28 | Mar 8 | Mar 16 | Mar 24 | Mar 30 | Apr 6 | Apr 20 | May 6 |
| 24°F98% of yrs | Jan 7 | Jan 27 | Feb 9 | Feb 17 | Feb 24 | Mar 1 | Mar 9 | Mar 21 | Apr 6 |
| 20°F77% of yrs | Dec 12 | Dec 30 | Jan 7 | Jan 18 | Jan 31 | Feb 10 | Feb 17 | Feb 25 | Mar 9 |
| 16°F39% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 6 | Oct 12 | Oct 17 | Oct 21 | Oct 24 | Oct 28 | Nov 1 | Nov 5 | Nov 10 |
| 32°F | Oct 21 | Oct 27 | Nov 1 | Nov 4 | Nov 7 | Nov 11 | Nov 16 | Nov 21 | Nov 26 |
| 28°F | Nov 3 | Nov 8 | Nov 13 | Nov 20 | Nov 24 | Nov 29 | Dec 3 | Dec 9 | Dec 16 |
| 24°F98% of yrs | Nov 15 | Nov 25 | Dec 1 | Dec 7 | Dec 12 | Dec 18 | Dec 24 | Dec 30 | Jan 16 |
| 20°F77% of yrs | Nov 24 | Dec 3 | Dec 12 | Dec 20 | Dec 27 | Jan 1 | Jan 9 | Jan 26 | Feb 14 |
| 16°F39% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Saint Helens Rfd, OR, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 97051 →Compare Saint Helens with another place →
Weather by month in Saint Helens
August is the warmest month at Saint Helens Rfd, OR, averaging 79°F by day and 55°F at night; December is the coldest at 42°F and 33°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 66% of years and May still brings one in 23% of years.
Warmth for growing adds up to 2,198 growing degree days a year (base 50°F), fewer than at 53% of the 103 Oregon stations. 29% of them (631) have built up by the end of June, and August adds the most, 530.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 43 | 33 | 99% | 14 | 0 |
| Feb | 47 | 33 | 99% | 12 | 1 |
| Mar | 53 | 36 | 96% | 8 | 15 |
| Apr | 59 | 40 | 66% | 3 | 68 |
| May | 67 | 46 | 23% | 1 | 215 |
| Jun | 72 | 50 | 8% | <1 | 331 |
| Jul | 79 | 55 | 0% | 0 | 524 |
| Aug | 79 | 55 | 0% | 0 | 530 |
| Sep | 74 | 52 | 0% | 0 | 381 |
| Oct | 61 | 45 | 30% | 1 | 121 |
| Nov | 49 | 38 | 95% | 8 | 10 |
| Dec | 42 | 33 | 100% | 12 | 0 |
Monthly normals 1991–2020 at Saint Helens Rfd, OR (269 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Scappoose Ind Airport, OR, 6 miles south of Saint Helens and 214 feet lower, has a last frost 8 days earlier (April 10), a first frost 5 days earlier (November 2), a season 8 days longer.
When it snows in Saint Helens, Oregon
Measurable snow is rare here: only 4 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Saint Helens Rfd, OR, 1.5 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 97051
| When | What to do |
|---|---|
| February 7 – February 21 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 21 – March 7 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 21 – April 4 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 18 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 15 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 24 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 7 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 97051 is 2 miles from Saint Helens Rfd, OR, which stands at 269 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 97051 in zone 8b, the band where the coldest night of the year averaged 15 to 20°F (-9.4 to -6.7°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.