USDA Hardiness Zone 9b
Frost Dates for 89005 — Boulder City, Nevada
NOAA 1991–2020 normals from Alan Bible Visitor Ctr, NV (1,641 ft), 4 miles northeast.
Updated
In Boulder City, the last spring frost (32°F) is around January 21 in half of years and has passed by March 5 in nine years out of ten. The first fall frost comes around December 17, as early as December 2 one year in ten, leaving a typical freeze-free season of 328 days (NOAA, Alan Bible Visitor Ctr, NV).
- Last spring frost
- January 21
- First fall frost
- December 17
- Growing season
- 328 days
- Hardiness zone
- 9b
50% probability
50% probability
freeze-free, 50%
25 to 30°F (-3.9 to -1.1°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 0%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
0 of 16 observed
NOAA normal
Frost risk by date in Boulder City
Half of springs at Alan Bible Visitor Ctr, NV see their last 32°F night by January 21; only one in ten is past it by December 29, and one in ten still has one after March 5. Planting tender crops after February 8 leaves a 30% risk of a frost on them, after February 20 20%, and after March 5 10%. The 43 days between the even-odds date and the one-in-ten date is the widest of the 38 Nevada 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 December 17 in half of years, as early as December 2 one year in ten, and holds off past January 3 one year in ten. A hard freeze of 28°F follows 13 days later, around December 30; in spring the one-in-ten date for 28°F is March 3, 2 days before the 32°F one. The freeze-free season lasts 328 days in a typical year, longer than at 95% of the 38 Nevada stations; it reaches 355 days one year in ten and falls short of 285 one year in ten. On average 5 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 23 days longer, to about February 13, and return around December 5. A 24°F night is unusual: 21% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jan 18 | Jan 27 | Feb 1 | Feb 6 | Feb 13 | Feb 19 | Feb 25 | Mar 4 | Mar 13 |
| 32°F98% of yrs | Dec 29 | Jan 5 | Jan 11 | Jan 16 | Jan 21 | Jan 29 | Feb 8 | Feb 20 | Mar 5 |
| 28°F63% of yrs | Dec 19 | Dec 27 | Jan 1 | Jan 5 | Jan 10 | Jan 16 | Jan 26 | Feb 17 | Mar 3 |
| 24°F21% of yrs | too rare for a date | ||||||||
| 20°F5% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 23 | Nov 28 | Dec 1 | Dec 3 | Dec 5 | Dec 8 | Dec 11 | Dec 14 | Dec 18 |
| 32°F98% of yrs | Dec 2 | Dec 6 | Dec 9 | Dec 13 | Dec 17 | Dec 20 | Dec 24 | Dec 27 | Jan 3 |
| 28°F63% of yrs | Dec 8 | Dec 14 | Dec 21 | Dec 26 | Dec 30 | Jan 2 | Jan 7 | Jan 16 | Feb 3 |
| 24°F21% of yrs | too rare for a date | ||||||||
| 20°F5% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Alan Bible Visitor Ctr, NV, 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 89005 →Compare Boulder City with another place →
Weather by month in Boulder City
July is the warmest month at Alan Bible Visitor Ctr, NV, averaging 107°F by day and 84°F at night; December is the coldest at 60°F and 40°F. From April to November the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 27% of years and March still brings one in 11% of years.
Warmth for growing adds up to 8,112 growing degree days a year (base 50°F), more than at 97% of the 38 Nevada stations. 40% of them (3,282) have built up by the end of June, and July adds the most, 1,417.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 60 | 41 | 79% | 2 | 68 |
| Feb | 64 | 45 | 27% | 1 | 156 |
| Mar | 73 | 52 | 11% | 1 | 385 |
| Apr | 81 | 59 | 0% | 0 | 588 |
| May | 91 | 66 | 0% | 0 | 887 |
| Jun | 103 | 77 | 0% | 0 | 1198 |
| Jul | 107 | 84 | 0% | 0 | 1417 |
| Aug | 105 | 82 | 0% | 0 | 1342 |
| Sep | 98 | 73 | 0% | 0 | 1062 |
| Oct | 84 | 59 | 0% | 0 | 667 |
| Nov | 69 | 50 | 8% | <1 | 285 |
| Dec | 60 | 40 | 84% | 2 | 58 |
Monthly normals 1991–2020 at Alan Bible Visitor Ctr, NV (1,641 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, Las Vegas Mccarran Airport, NV, 20 miles west of Boulder City and 490 feet higher, has a last frost 1 day earlier (January 20), a first frost 2 days earlier (December 15), a season 5 days longer.
When it snows in Boulder City, Nevada
Measurable snow is rare here: only 0 of 16 winters from 1991 to 2020 recorded 0.1 inch or more at Willow Beach, AZ, 11.9 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 89005
| When | What to do |
|---|---|
| November 12 – November 26 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| November 26 – December 10 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| December 24 – January 7 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| January 21 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 24 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by December 3 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 17 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 89005 is 4 miles from Alan Bible Visitor Ctr, NV, which stands at 1,641 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 89015 (Henderson). The 2023 USDA Plant Hardiness Zone Map lists ZIP 89005 in zone 9b, the band where the coldest night of the year averaged 25 to 30°F (-3.9 to -1.1°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.