USDA Hardiness Zone 8a
Frost Dates for 97064 — Vernonia, Oregon
NOAA 1991–2020 normals from Vernonia #2, OR (625 ft), under a mile east.
Updated
In Vernonia, the last spring frost (32°F) is around May 8 in half of years and has passed by May 29 in nine years out of ten. The first fall frost comes around October 1, as early as September 11 one year in ten, leaving a typical freeze-free season of 144 days (NOAA, Vernonia #2, OR).
- Last spring frost
- May 8
- First fall frost
- October 1
- Growing season
- 144 days
- Hardiness zone
- 8a
50% probability
50% probability
freeze-free, 50%
10 to 15°F (-12.2 to -9.4°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 19%
- Snow per year
- 1.1"
median, 1991–2020
median, 1991–2020
5 of 27 observed
NOAA normal
Frost risk by date in Vernonia
Half of springs at Vernonia #2, OR see their last 32°F night by May 8; only one in ten is past it by April 18, and one in ten still has one after May 29. Planting tender crops after May 17 leaves a 30% risk of a frost on them, after May 23 20%, and after May 29 10%. The 21 days between the even-odds date and the one-in-ten date is narrower than at 55% 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 October 1 in half of years, as early as September 11 one year in ten, and holds off past October 28 one year in ten. A hard freeze of 28°F follows 20 days later, around October 21; in spring the one-in-ten date for 28°F is May 7, 22 days before the 32°F one. The freeze-free season lasts 144 days in a typical year, shorter than at 82% of the 103 Oregon stations; it reaches 178 days one year in ten and falls short of 114 one year in ten. On average 99 nights a year drop to 32°F or below. Nights of 24°F, cold enough to damage hardier plants, come in 100% of winters and 16°F in 69%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Apr 18 | Apr 26 | Apr 30 | May 2 | May 8 | May 12 | May 17 | May 23 | May 29 |
| 28°F | Mar 14 | Mar 25 | Apr 1 | Apr 7 | Apr 12 | Apr 19 | Apr 26 | May 1 | May 7 |
| 24°F | Feb 2 | Feb 18 | Feb 23 | Feb 28 | Mar 5 | Mar 12 | Mar 18 | Mar 26 | Apr 5 |
| 20°F95% of yrs | Dec 18 | Jan 6 | Jan 17 | Feb 1 | Feb 12 | Feb 18 | Feb 23 | Feb 28 | Mar 6 |
| 16°F69% of yrs | Dec 3 | Dec 12 | Dec 26 | Jan 2 | Jan 14 | Jan 29 | Feb 9 | Feb 18 | Feb 25 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Sep 11 | Sep 18 | Sep 24 | Sep 28 | Oct 1 | Oct 6 | Oct 10 | Oct 18 | Oct 28 |
| 28°F | Sep 28 | Oct 3 | Oct 8 | Oct 15 | Oct 21 | Oct 26 | Nov 1 | Nov 9 | Nov 19 |
| 24°F | Oct 14 | Oct 25 | Nov 1 | Nov 9 | Nov 15 | Nov 23 | Nov 28 | Dec 6 | Dec 20 |
| 20°F95% of yrs | Nov 4 | Nov 14 | Nov 23 | Nov 29 | Dec 5 | Dec 14 | Dec 24 | Jan 1 | Jan 20 |
| 16°F69% of yrs | Nov 13 | Nov 27 | Dec 3 | Dec 9 | Dec 17 | Dec 27 | Jan 2 | Jan 22 | Feb 14 |
Freeze probabilities 1991–2020 at Vernonia #2, 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 97064 →Compare Vernonia with another place →
Weather by month in Vernonia
August is the warmest month at Vernonia #2, OR, averaging 78°F by day and 47°F at night; December is the coldest at 44°F and 31°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 62% of years.
Warmth for growing adds up to 1,476 growing degree days a year (base 50°F), fewer than at 90% of the 103 Oregon stations. 26% of them (388) have built up by the end of June, and August adds the most, 389. Precipitation totals 47.9 inches a year, most in December (8.3") and least in July (0.4"); May to September bring 14% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 46 | 32 | 6.9 | 100% | 17 | 1 |
| Feb | 49 | 31 | 5.3 | 100% | 17 | 1 |
| Mar | 54 | 34 | 5.3 | 100% | 15 | 8 |
| Apr | 59 | 36 | 3.7 | 97% | 9 | 33 |
| May | 66 | 40 | 2.4 | 62% | 3 | 127 |
| Jun | 70 | 44 | 1.4 | 5% | 0 | 219 |
| Jul | 77 | 47 | 0.4 | 0% | 0 | 380 |
| Aug | 78 | 47 | 0.6 | 0% | 0 | 389 |
| Sep | 73 | 43 | 1.8 | 46% | 2 | 244 |
| Oct | 61 | 38 | 4.1 | 89% | 7 | 67 |
| Nov | 51 | 34 | 7.7 | 99% | 12 | 8 |
| Dec | 44 | 31 | 8.3 | 100% | 17 | 1 |
Monthly normals 1991–2020 at Vernonia #2, OR (625 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, Saint Helens Rfd, OR, 16 miles east of Vernonia and 356 feet lower, has a last frost 20 days earlier (April 18), a first frost 37 days later (November 7), a season 57 days longer.
When it snows in Vernonia, Oregon
Measurable snow is rare here: only 5 of 27 winters from 1991 to 2020 recorded 0.1 inch or more at Vernonia #2, OR, 0.8 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 97064
| When | What to do |
|---|---|
| February 27 – March 13 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 13 – March 27 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 10 – April 24 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 8 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 9 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 17 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 1 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 97064 is under a mile from Vernonia #2, OR, which stands at 625 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 97064 in zone 8a, the band where the coldest night of the year averaged 10 to 15°F (-12.2 to -9.4°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.