USDA Hardiness Zone 6b
Frost Dates for 83854 — Post Falls, Idaho
NOAA 1991–2020 normals from Coeur D'Alene, ID (2,133 ft), 7 miles east.
Updated
In Post Falls, the last spring frost (32°F) is around April 22 in half of years and has passed by May 6 in nine years out of ten. The first fall frost comes around October 18, as early as October 4 one year in ten, leaving a typical freeze-free season of 179 days (NOAA, Coeur D'Alene, ID).
- Last spring frost
- April 22
- First fall frost
- October 18
- Growing season
- 179 days
- Hardiness zone
- 6b
50% probability
50% probability
freeze-free, 50%
-5 to 0°F (-20.6 to -17.8°C) coldest night
- First snow
- November 28
- Last snow
- March 1
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
21 of 21 observed
NOAA normal
Frost risk by date in Post Falls
Half of springs at Coeur D'Alene, ID see their last 32°F night by April 22; only one in ten is past it by April 4, and one in ten still has one after May 6. Planting tender crops after April 29 leaves a 30% risk of a frost on them, after May 2 20%, and after May 6 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 93% of the 67 Idaho stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 18 in half of years, as early as October 4 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 14 days later, around November 1; in spring the one-in-ten date for 28°F is April 21, 15 days before the 32°F one. The freeze-free season lasts 179 days in a typical year, longer than at 91% of the 67 Idaho stations; it reaches 202 days one year in ten and falls short of 158 one year in ten. On average 120 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 15 days longer, to about May 7, and return around October 6. Severe cold of 16°F or below comes in 98% of winters, usually between December 8 and February 15.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 25 | Apr 29 | May 1 | May 4 | May 7 | May 9 | May 12 | May 15 | May 21 |
| 32°F | Apr 4 | Apr 10 | Apr 14 | Apr 19 | Apr 22 | Apr 26 | Apr 29 | May 2 | May 6 |
| 28°F | Mar 13 | Mar 20 | Mar 24 | Mar 29 | Apr 1 | Apr 4 | Apr 7 | Apr 13 | Apr 21 |
| 24°F | Feb 23 | Mar 1 | Mar 5 | Mar 8 | Mar 12 | Mar 15 | Mar 19 | Mar 22 | Mar 29 |
| 20°F | Feb 3 | Feb 14 | Feb 21 | Feb 26 | Mar 1 | Mar 4 | Mar 8 | Mar 12 | Mar 16 |
| 16°F98% of yrs | Jan 5 | Jan 22 | Feb 2 | Feb 9 | Feb 15 | Feb 22 | Feb 28 | Mar 3 | Mar 9 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 23 | Sep 28 | Oct 1 | Oct 3 | Oct 6 | Oct 9 | Oct 12 | Oct 16 | Oct 21 |
| 32°F | Oct 4 | Oct 8 | Oct 12 | Oct 15 | Oct 18 | Oct 22 | Oct 25 | Oct 30 | Nov 5 |
| 28°F | Oct 15 | Oct 21 | Oct 25 | Oct 29 | Nov 1 | Nov 5 | Nov 8 | Nov 12 | Nov 20 |
| 24°F | Oct 24 | Nov 1 | Nov 6 | Nov 9 | Nov 13 | Nov 18 | Nov 22 | Nov 26 | Dec 2 |
| 20°F | Nov 2 | Nov 10 | Nov 17 | Nov 23 | Nov 26 | Nov 30 | Dec 4 | Dec 11 | Dec 23 |
| 16°F98% of yrs | Nov 15 | Nov 25 | Nov 30 | Dec 4 | Dec 8 | Dec 16 | Dec 23 | Dec 30 | Jan 12 |
Freeze probabilities 1991–2020 at Coeur D'Alene, ID, 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 83854 →Compare Post Falls with another place →
Weather by month in Post Falls
July is the warmest month at Coeur D'Alene, ID, averaging 83°F by day and 57°F at night; January is the coldest at 36°F and 26°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 25% of years.
Warmth for growing adds up to 2,202 growing degree days a year (base 50°F), fewer than at 51% of the 67 Idaho stations. 26% of them (573) have built up by the end of June, and July adds the most, 621. Precipitation totals 25.3 inches a year, most in December (3.5") and least in July (0.7"); May to September bring 26% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 36 | 26 | 3.2 | 100% | 25 | 0 |
| Feb | 41 | 27 | 2.1 | 100% | 23 | 0 |
| Mar | 48 | 31 | 2.7 | 100% | 19 | 2 |
| Apr | 56 | 37 | 1.9 | 92% | 7 | 37 |
| May | 66 | 44 | 2.1 | 25% | 1 | 186 |
| Jun | 72 | 51 | 2.2 | 0% | 0 | 348 |
| Jul | 83 | 57 | 0.7 | 0% | 0 | 621 |
| Aug | 83 | 56 | 0.8 | 0% | 0 | 604 |
| Sep | 74 | 48 | 0.8 | 6% | <1 | 335 |
| Oct | 58 | 39 | 2.0 | 82% | 6 | 65 |
| Nov | 44 | 32 | 3.3 | 100% | 15 | 3 |
| Dec | 36 | 26 | 3.5 | 100% | 25 | 0 |
Monthly normals 1991–2020 at Coeur D'Alene, ID (2,133 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, Spokane Felts Field, WA, 18 miles west of Post Falls and 180 feet lower, has a last frost 4 days later (April 26), a first frost 3 days earlier (October 15), a season 9 days shorter.
When it snows in Post Falls, Idaho
The first measurable snow (0.1 inch or more) in Post Falls usually arrives around November 28, and the last of the season around March 1. Those are the middle dates across the winters of 1991–2020 at Coeur D'Alene, ID, 7.4 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 52 days after the last snow.
Planting calendar for 83854
| When | What to do |
|---|---|
| February 11 – February 25 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 25 – March 11 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 25 – April 8 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 22 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 26 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 4 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 18 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 83854 is 7 miles from Coeur D'Alene, ID, which stands at 2,133 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 83854 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°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.