USDA Hardiness Zone 6a
Frost Dates for 99166 — Republic, Washington
NOAA 1991–2020 normals from Republic, WA (2,555 ft), under a mile southwest.
Updated
In Republic, the last spring frost (32°F) is around May 30 in half of years and has passed by June 17 in nine years out of ten. The first fall frost comes around September 10, as early as August 28 one year in ten, leaving a typical freeze-free season of 102 days (NOAA, Republic, WA).
- Last spring frost
- May 30
- First fall frost
- September 10
- Growing season
- 102 days
- Hardiness zone
- 6a
50% probability
50% probability
freeze-free, 50%
-10 to -5°F (-23.3 to -20.6°C) coldest night
- First snow
- November 8
- Last snow
- March 14
- Winters with snow
- 100%
- Snow per year
- 52.5"
median, 1991–2020
median, 1991–2020
26 of 26 observed
NOAA normal
Frost risk by date in Republic
Half of springs at Republic, WA see their last 32°F night by May 30; only one in ten is past it by May 11, and one in ten still has one after June 17. Planting tender crops after June 5 leaves a 30% risk of a frost on them, after June 11 20%, and after June 17 10%. The 18 days between the even-odds date and the one-in-ten date is narrower than at 56% of the 113 Washington stations behind this site's ZIP pages.
In fall the first 32°F night comes by September 10 in half of years, as early as August 28 one year in ten, and holds off past September 25 one year in ten. A hard freeze of 28°F follows 14 days later, around September 24; in spring the one-in-ten date for 28°F is May 28, 20 days before the 32°F one. The freeze-free season lasts 102 days in a typical year, shorter than at 98% of the 113 Washington stations; it reaches 125 days one year in ten and falls short of 79 one year in ten. On average 188 nights a year drop to 32°F or below. Severe cold of 16°F or below comes every winter, usually between October 31 and March 17.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | May 11 | May 17 | May 23 | May 27 | May 30 | Jun 1 | Jun 5 | Jun 11 | Jun 17 |
| 28°F | Apr 27 | Apr 30 | May 5 | May 8 | May 12 | May 14 | May 17 | May 22 | May 28 |
| 24°F | Apr 11 | Apr 17 | Apr 20 | Apr 24 | Apr 27 | Apr 30 | May 3 | May 7 | May 12 |
| 20°F | Mar 19 | Mar 27 | Mar 31 | Apr 3 | Apr 6 | Apr 9 | Apr 15 | Apr 21 | Apr 28 |
| 16°F | Mar 3 | Mar 7 | Mar 11 | Mar 14 | Mar 17 | Mar 20 | Mar 26 | Mar 30 | Apr 4 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Aug 28 | Sep 2 | Sep 5 | Sep 7 | Sep 10 | Sep 13 | Sep 16 | Sep 20 | Sep 25 |
| 28°F | Sep 11 | Sep 15 | Sep 18 | Sep 21 | Sep 24 | Sep 26 | Sep 29 | Oct 1 | Oct 5 |
| 24°F | Sep 23 | Sep 28 | Oct 1 | Oct 2 | Oct 5 | Oct 7 | Oct 11 | Oct 14 | Oct 19 |
| 20°F | Oct 1 | Oct 6 | Oct 10 | Oct 14 | Oct 18 | Oct 22 | Oct 25 | Oct 30 | Nov 5 |
| 16°F | Oct 12 | Oct 19 | Oct 24 | Oct 29 | Oct 31 | Nov 3 | Nov 7 | Nov 13 | Nov 20 |
Freeze probabilities 1991–2020 at Republic, 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 99166 →Compare Republic with another place →
Weather by month in Republic
July is the warmest month at Republic, WA, averaging 84°F by day and 47°F at night; December is the coldest at 30°F and 16°F. A freezing night is all but certain in every month from September to May (a 90% chance or more). July is the only month with under a 10% chance of a 32°F night. In spring, June still brings one in 44% of years.
Warmth for growing adds up to 1,547 growing degree days a year (base 50°F), fewer than at 87% of the 113 Washington stations. 26% of them (395) have built up by the end of June, and July adds the most, 475. Precipitation totals 18.2 inches a year, most in June (2.2") and least in August (0.6"); May to September bring 38% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 31 | 16 | 1.6 | 100% | 30 | 0 |
| Feb | 38 | 18 | 1.3 | 100% | 26 | 0 |
| Mar | 49 | 24 | 1.5 | 100% | 27 | 1 |
| Apr | 58 | 29 | 1.4 | 100% | 19 | 17 |
| May | 68 | 37 | 2.1 | 98% | 7 | 127 |
| Jun | 74 | 42 | 2.2 | 44% | <1 | 250 |
| Jul | 84 | 47 | 1.2 | 0% | 0 | 475 |
| Aug | 84 | 45 | 0.6 | 16% | <1 | 453 |
| Sep | 74 | 38 | 0.9 | 96% | 5 | 203 |
| Oct | 57 | 29 | 1.3 | 100% | 19 | 22 |
| Nov | 40 | 23 | 1.9 | 100% | 25 | 0 |
| Dec | 30 | 16 | 2.2 | 100% | 30 | 0 |
Monthly normals 1991–2020 at Republic, WA (2,555 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, Tonasket 4 NNE, WA, 33 miles west of Republic and 1,595 feet lower, has a last frost 34 days earlier (April 26), a first frost 30 days later (October 10), a season 66 days longer.
When it snows in Republic, Washington
The first measurable snow (0.1 inch or more) in Republic usually arrives around November 8, and the last of the season around March 14. Those are the middle dates across the winters of 1991–2020 at Republic, WA, 0.9 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 77 days after the last snow.
Planting calendar for 99166
| When | What to do |
|---|---|
| March 21 – April 4 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| April 4 – April 18 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| May 2 – May 16 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 30 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by June 18 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by August 27 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 10 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 99166 is under a mile from Republic, WA, which stands at 2,555 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 99166 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°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.