Frost dates for ZIP 99357 (Royal City, WA)
Average last spring and first fall frost dates with 10%, 50% and 90% odds, from NOAA's 1991–2020 climate normals for the nearest weather station, Smyrna, WA (4 miles away).
- Average last spring frostApr 2350% chance of a 32°F freeze after this date
- Average first fall frostOct 1250% chance of a 32°F freeze by this date
- Growing season (frost-free)172 daysmedian, 32°F threshold
- USDA hardiness zone7a0 to 5°F avg. coldest night
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This week in your yard
As of Oct 17, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
56°F 55°F or warmer
24-hour average · latest 60°F, as of Oct 17, 10:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Lind #1 (52 mi).
4-inch depth
56°F 55°F or warmer
24-hour average · latest 58°F, as of Oct 17, 10:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Lind #1 (52 mi).
Fall: Texas A&M AgriLife times fall pre-emergent (for winter weeds such as annual bluegrass) to soil cooling to about 70°F for several days. The 50–55°F band is the spring trigger. Always read and follow the product label.
7-day forecast and frost risk
The latest National Weather Service 7-day forecast and any Frost Advisory or Freeze Warning for 99357 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 56°F at 4 inches (estimated soil temperature, not a station reading). Fall pre-emergent (annual bluegrass, winter weeds): window open as soil cools through the 70s and 60s.
Fertilizer window
Lawn region: Mountain West and High Plains. Timing only; always follow the product label.
- Kentucky bluegrass (cool-season): Early fall: Around Labor Day (late August–September); Late fall: Late October–November, before the ground freezes; Late spring: Optional around Memorial Day. Avoid: Early-spring and midsummer feeding (pushes top growth, favors crabgrass).
Plant now
No vegetable planting windows are open this week.
Prune now
No frost-timed pruning windows are open this week.
Spring-flowering shrubs are pruned right after their flowers fade, not by date. See the pruning guide.
Last spring frost odds
| Chance of a 32°F freeze after this date | Date |
|---|---|
| 90% (early: most years still freeze after this) | Apr 3 |
| 50% (the "average" last frost) | Apr 23 |
| 10% (cautious: only 1 year in 10 freezes later) | May 7 |
Most gardeners plant frost-tender crops (tomatoes, peppers, basil) after the 50% date, and closer to the 10% date for less risk.
First fall frost odds
| Chance the first 32°F freeze has happened by this date | Date |
|---|---|
| 10% (early: 1 year in 10 freezes this soon) | Oct 1 |
| 50% (the "average" first frost) | Oct 12 |
| 90% (late: most years have frozen by now) | Oct 25 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 6 | Oct 2 |
| 32°F (freeze) | Apr 23 | Oct 12 |
| 28°F (hard freeze) | Apr 3 | Oct 24 |
n/a means NOAA did not publish a date at that threshold for this station (usually because it rarely gets that cold).
Vegetable planting calendar for 99357
Dates count from your average last spring frost (Apr 23) and first fall frost (Oct 12). Half of years have a frost after the spring date, so give tender crops (tomatoes, peppers, squash) some slack.
| Crop | Start indoors | Spring planting | Fall planting |
|---|---|---|---|
| Tomato | Feb 26–Mar 12 | Apr 30–May 14 (transplant) | – |
| Pepper (sweet and hot) | Feb 12–26 | May 7–21 (transplant) | – |
| Eggplant | Feb 12–26 | May 7–21 (transplant) | – |
| Tomatillo | Feb 26–Mar 12 | Apr 30–May 14 (transplant) | – |
| Lettuce | Feb 26–Mar 12 | Apr 2–23 (transplant) Mar 26–May 7 (sow outdoors) | Aug 17–Sep 7 (transplant) Aug 3–31 (sowing) |
| Spinach | – | Mar 12–Apr 2 (sow outdoors) | Aug 17–Sep 7 (sowing) |
| Kale | Feb 26–Mar 12 | Mar 26–Apr 9 (transplant) Mar 26–Apr 9 (sow outdoors) | Jul 20–Aug 17 (transplant) Jul 6–Aug 3 (sowing) |
| Collards | Feb 26–Mar 12 | Mar 26–Apr 23 (transplant) Mar 26–Apr 23 (sow outdoors) | Jul 20–Aug 17 (transplant) Jul 6–Aug 3 (sowing) |
| Broccoli | Feb 12–26 | Mar 26–Apr 9 (transplant) | Jul 6–Aug 3 (transplant) |
| Cabbage | Feb 12–26 | Mar 26–Apr 9 (transplant) | Jul 6–Aug 3 (transplant) |
| Cauliflower | Feb 12–26 | Apr 9–23 (transplant) | Jul 6–Aug 3 (transplant) |
| Brussels sprouts | Jan 29–Feb 12 | Mar 26–Apr 9 (transplant) | Jun 22–Jul 13 (transplant) |
| Kohlrabi | Feb 26–Mar 12 | Mar 26–Apr 9 (transplant) Mar 26–Apr 9 (sow outdoors) | Aug 3–17 (sowing) |
| Bok choy / Asian greens | – | Mar 26–Apr 9 (sow outdoors) | Aug 17–31 (sowing) |
| Arugula | – | Mar 26–Apr 23 (sow outdoors) | Aug 17–Sep 14 (sowing) |
| Mustard greens | – | Mar 26–Apr 16 (sow outdoors) | Aug 17–31 (sowing) |
| Swiss chard | Mar 12–26 | Apr 9–30 (transplant) Apr 9–May 7 (sow outdoors) | Aug 3–17 (sowing) |
| Beet | – | Mar 26–Apr 23 (sow outdoors) | Aug 3–17 (sowing) |
| Carrot | – | Apr 2–30 (sow outdoors) | Jul 20–Aug 3 (sowing) |
| Radish | – | Mar 19–Apr 30 (sow outdoors) | Aug 31–Sep 14 (sowing) |
| Turnip | – | Mar 26–Apr 16 (sow outdoors) | Aug 3–17 (sowing) |
| Parsnip | – | Apr 2–23 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Feb 26–Mar 26 (sow outdoors) | Jul 20–Aug 3 (sowing) |
| Onion (bulbing) | Jan 29–Feb 12 | Mar 12–26 (transplant) | – |
| Green onion / scallion | – | Mar 12–Apr 9 (sow outdoors) | Aug 3–17 (sowing) |
| Leek | Jan 29–Feb 12 | Mar 26–Apr 9 (transplant) | – |
| Garlic | – | – | Aug 31–Sep 28 (sowing) |
| Shallot | – | Mar 12–26 (transplant) | Aug 31–Sep 28 (sowing) |
| Potato | – | Mar 26–Apr 9 (transplant) | Jun 22–Jul 6 (transplant) |
| Sweet potato | – | May 14–28 (transplant) | – |
| Sweet corn | – | Apr 30–May 14 (sow outdoors) | – |
| Bean, bush (snap) | – | Apr 30–May 14 (sow outdoors) | – |
| Bean, pole | – | Apr 30–May 14 (sow outdoors) | – |
| Lima bean | – | May 7–21 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 14–Jun 4 (sow outdoors) | – |
| Cucumber | Mar 26–Apr 2 | Apr 30–May 14 (transplant) Apr 30–May 14 (sow outdoors) | – |
| Summer squash / zucchini | Mar 26–Apr 2 | Apr 30–May 14 (transplant) Apr 30–May 14 (sow outdoors) | – |
| Winter squash | Mar 26–Apr 2 | Apr 30–May 14 (transplant) Apr 30–May 14 (sow outdoors) | – |
| Pumpkin | – | Apr 30–May 14 (sow outdoors) | – |
| Watermelon | Mar 26–Apr 2 | May 7–21 (transplant) May 7–21 (sow outdoors) | – |
| Cantaloupe / muskmelon | Mar 26–Apr 2 | May 7–21 (transplant) May 7–21 (sow outdoors) | – |
| Okra | Mar 12–26 | May 7–21 (transplant) May 7–21 (sow outdoors) | – |
| Celery | Jan 29–Feb 12 | Apr 30–May 7 (transplant) | – |
| Basil | Mar 12–26 | Apr 30–May 14 (transplant) Apr 30–May 14 (sow outdoors) | – |
| Cilantro | – | Apr 9–May 7 (sow outdoors) | Aug 17–31 (sowing) |
| Parsley | Feb 12–26 | Apr 9–23 (transplant) Apr 2–23 (sow outdoors) | – |
| Dill | – | Apr 23–May 7 (sow outdoors) | Aug 17–31 (sowing) |
| Sunflower | – | Apr 23–May 7 (sow outdoors) | – |
| Asparagus (crowns) | – | Mar 26–Apr 9 (transplant) | – |
| Rhubarb (crowns) | – | Mar 26–Apr 9 (transplant) | – |
| Strawberry (plants) | – | Mar 26–Apr 9 (transplant) | Aug 3–31 (transplant) |
Typical ranges from university extension planting calendars, adjusted to your frost dates. Probabilities, not guarantees. Fall windows that would overlap spring planting are left out, as are fall crops of frost-tender plants where the frost-free season is under 210 days.
Where these numbers come from
Station: Smyrna, WA (NOAA GHCN-Daily ID USC00457727), elevation 560 ft, 3.8 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Priest Rapids Dam, WA | 21 mi | Mar 24 | Nov 4 |
| Quincy, WA | 25 mi | Apr 21 | Oct 16 |
| Moses Lake Grant Co AP, WA | 27 mi | Apr 27 | Oct 8 |
The average last-frost dates of these stations span 34 days, a rough guide to local variation. See data sources & methods.
Frost questions for 99357
When is the last frost in 99357?
The average (50% chance) last spring freeze of 32°F for ZIP 99357 is April 23. For a more cautious planting date, use May 7, when only 1 year in 10 still sees a later freeze.
When is the first frost in 99357?
The average first fall freeze is October 12. In 1 year in 10 it comes by October 1.
What hardiness zone is 99357?
ZIP 99357 is in USDA zone 7a (0 to 5°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 99357 right now?
This page shows the latest 2-inch and 4-inch soil temperature from the nearest public soil station (USDA SCAN, NOAA USCRN or TexMesonet), or a labeled estimate when no station is close, against the 50–55°F spring pre-emergent band.
Nearby ZIP codes
99321 Schwana 99349 Desert Aire 98950 Vantage 98824 George 98848 Quincy 99344 Othello 98837 Moses Lake 98944 Sunnyside
Other ZIP codes in Grant County
98823 98824 98832 98837 98848 98851 98853 98857 98860 99123 99135 99321 99349 All Grant County frost dates · Washington frost dates
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