USDA Hardiness Zone 8b
Frost Dates for 98290 — Snohomish, Washington
NOAA 1991–2020 normals from Monroe, WA (120 ft), 6 miles south.
Updated
In Snohomish, the last spring frost (32°F) is around April 17 in half of years and has passed by May 7 in nine years out of ten. The first fall frost comes around October 23, as early as October 7 one year in ten, leaving a typical freeze-free season of 188 days (NOAA, Monroe, WA).
- Last spring frost
- April 17
- First fall frost
- October 23
- Growing season
- 188 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
- 16%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
3 of 19 observed
NOAA normal
Frost risk by date in Snohomish
Half of springs at Monroe, WA see their last 32°F night by April 17; only one in ten is past it by March 29, and one in ten still has one after May 7. Planting tender crops after April 27 leaves a 30% risk of a frost on them, after May 1 20%, and after May 7 10%. The 20 days between the even-odds date and the one-in-ten date is wider than at 52% of the 113 Washington stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 23 in half of years, as early as October 7 one year in ten, and holds off past November 9 one year in ten. A hard freeze of 28°F follows 16 days later, around November 8; in spring the one-in-ten date for 28°F is April 14, 23 days before the 32°F one. The freeze-free season lasts 188 days in a typical year, shorter than at 51% of the 113 Washington stations; it reaches 212 days one year in ten and falls short of 163 one year in ten. On average 60 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 5, and return around October 6. Nights of 24°F, cold enough to damage hardier plants, come in 100% of winters and 16°F in 54%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 20 | Apr 26 | Apr 29 | May 2 | May 5 | May 8 | May 11 | May 15 | May 20 |
| 32°F | Mar 29 | Apr 3 | Apr 8 | Apr 12 | Apr 17 | Apr 22 | Apr 27 | May 1 | May 7 |
| 28°F | Mar 6 | Mar 13 | Mar 17 | Mar 22 | Mar 26 | Mar 29 | Apr 2 | Apr 7 | Apr 14 |
| 24°F | Jan 31 | Feb 13 | Feb 19 | Feb 25 | Feb 28 | Mar 4 | Mar 10 | Mar 15 | Mar 22 |
| 20°F89% of yrs | Dec 10 | Dec 30 | Jan 8 | Jan 23 | Feb 2 | Feb 11 | Feb 18 | Feb 24 | Feb 28 |
| 16°F54% of yrs | Nov 30 | Dec 8 | Dec 13 | Dec 25 | Jan 4 | Jan 14 | Jan 27 | Feb 6 | Feb 18 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 21 | Sep 27 | Oct 1 | Oct 3 | Oct 6 | Oct 10 | Oct 14 | Oct 18 | Oct 25 |
| 32°F | Oct 7 | Oct 13 | Oct 16 | Oct 20 | Oct 23 | Oct 27 | Oct 31 | Nov 4 | Nov 9 |
| 28°F | Oct 20 | Oct 27 | Nov 1 | Nov 4 | Nov 8 | Nov 11 | Nov 14 | Nov 20 | Nov 26 |
| 24°F | Nov 1 | Nov 9 | Nov 14 | Nov 18 | Nov 23 | Nov 28 | Dec 3 | Dec 10 | Dec 22 |
| 20°F89% of yrs | Nov 13 | Nov 20 | Nov 27 | Dec 2 | Dec 9 | Dec 16 | Dec 26 | Jan 3 | Jan 26 |
| 16°F54% of yrs | Nov 19 | Nov 28 | Dec 4 | Dec 9 | Dec 15 | Dec 24 | Jan 2 | Jan 15 | Feb 1 |
Freeze probabilities 1991–2020 at Monroe, WA, 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 98290 →Compare Snohomish with another place →
Weather by month in Snohomish
August is the warmest month at Monroe, WA, averaging 75°F by day and 52°F at night; December is the coldest at 43°F and 32°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 83% of years and May still brings one in 21% of years.
Warmth for growing adds up to 1,550 growing degree days a year (base 50°F), fewer than at 86% of the 113 Washington stations. 28% of them (431) have built up by the end of June, and August adds the most, 406. Precipitation totals 50.8 inches a year, most in November (7.2") and least in July (1.2"); May to September bring 22% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 44 | 32 | 6.5 | 100% | 13 | 1 |
| Feb | 48 | 32 | 4.5 | 100% | 12 | 1 |
| Mar | 52 | 35 | 5.2 | 100% | 8 | 7 |
| Apr | 57 | 39 | 4.3 | 83% | 3 | 32 |
| May | 64 | 44 | 3.4 | 21% | <1 | 140 |
| Jun | 68 | 49 | 2.7 | 0% | 0 | 250 |
| Jul | 74 | 52 | 1.2 | 0% | 0 | 403 |
| Aug | 75 | 52 | 1.3 | 0% | 0 | 406 |
| Sep | 69 | 48 | 2.7 | 0% | 0 | 247 |
| Oct | 58 | 41 | 5.0 | 72% | 2 | 58 |
| Nov | 49 | 35 | 7.2 | 100% | 9 | 5 |
| Dec | 43 | 32 | 6.8 | 100% | 14 | 0 |
Monthly normals 1991–2020 at Monroe, WA (120 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, Everett, WA, 8 miles northwest of Snohomish, has a last frost 24 days earlier (March 24), a first frost 10 days later (November 2), a season 35 days longer.
When it snows in Snohomish, Washington
Measurable snow is rare here: only 3 of 19 winters from 1991 to 2020 recorded 0.1 inch or more at Startup 1 E, WA, 15.6 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 98290
| When | What to do |
|---|---|
| February 6 – February 20 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 20 – March 6 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 20 – April 3 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 17 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 31 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 9 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 23 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 98290 is 6 miles from Monroe, WA, which stands at 120 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 98290 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.
Frost dates across Washington →
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.