Fall in zone 9aPhoto: George Chernilevsky, Public domain, via Wikimedia Commons
Frost dates for ZIP 98250 (Roche Harbor, 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, Friday Harbor AP, WA (4 miles away).
- Average last spring frostMar 2650% chance of a 32°F freeze after this date
- Average first fall frostNov 1050% chance of a 32°F freeze by this date
- Growing season (frost-free)230 daysmedian, 32°F threshold
- USDA hardiness zone9a20 to 25°F avg. coldest night
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This week in your yard
As of Oct 18, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
No soil station with a fresh reading within 62 miles.
4-inch depth
No soil station with a fresh reading within 62 miles.
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 98250 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
No soil reading near this ZIP. Typical extension timing for your region: spring March to April.
Fertilizer window
Lawn region: Pacific Northwest (west of the Cascades). Timing only; always follow the product label.
- Perennial ryegrass (cool-season): Early fall: September; Late fall: October–November; Overseeded Bermuda: Light feeding once the winter rye is established, if needed. Avoid: Summer feeding.
Plant now
Prune now
No frost-timed pruning windows are open this week.
Your average first frost is Nov 10: skip heavy pruning in the 6–8 weeks before it, because new growth may not harden off in time.
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) | Feb 25 |
| 50% (the "average" last frost) | Mar 26 |
| 10% (cautious: only 1 year in 10 freezes later) | Apr 21 |
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 21 |
| 50% (the "average" first frost) | Nov 10 |
| 90% (late: most years have frozen by now) | Dec 1 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Apr 29 | Oct 24 |
| 32°F (freeze) | Mar 26 | Nov 10 |
| 28°F (hard freeze) | Feb 22 | Dec 1 |
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 98250
Dates count from your average last spring frost (Mar 26) and first fall frost (Nov 10). 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 | Jan 29–Feb 12 | Apr 2–16 (transplant) | Jul 14–Aug 11 (transplant) |
| Pepper (sweet and hot) | Jan 15–29 | Apr 9–23 (transplant) | Jul 21–Aug 11 (transplant) |
| Eggplant | Jan 15–29 | Apr 9–23 (transplant) | Jul 21–Aug 11 (transplant) |
| Tomatillo | Jan 29–Feb 12 | Apr 2–16 (transplant) | – |
| Lettuce | Jan 29–Feb 12 | Mar 5–26 (transplant) Feb 26–Apr 9 (sow outdoors) | Sep 15–Oct 6 (transplant) Sep 1–29 (sowing) |
| Spinach | – | Feb 12–Mar 5 (sow outdoors) | Sep 15–Oct 6 (sowing) |
| Kale | Jan 29–Feb 12 | Feb 26–Mar 12 (transplant) Feb 26–Mar 12 (sow outdoors) | Aug 18–Sep 15 (transplant) Aug 4–Sep 1 (sowing) |
| Collards | Jan 29–Feb 12 | Feb 26–Mar 26 (transplant) Feb 26–Mar 26 (sow outdoors) | Aug 18–Sep 15 (transplant) Aug 4–Sep 1 (sowing) |
| Broccoli | Jan 15–29 | Feb 26–Mar 12 (transplant) | Aug 4–Sep 1 (transplant) |
| Cabbage | Jan 15–29 | Feb 26–Mar 12 (transplant) | Aug 4–Sep 1 (transplant) |
| Cauliflower | Jan 15–29 | Mar 12–26 (transplant) | Aug 4–Sep 1 (transplant) |
| Brussels sprouts | Jan 1–15 | Feb 26–Mar 12 (transplant) | Jul 21–Aug 11 (transplant) |
| Kohlrabi | Jan 29–Feb 12 | Feb 26–Mar 12 (transplant) Feb 26–Mar 12 (sow outdoors) | Sep 1–15 (sowing) |
| Bok choy / Asian greens | – | Feb 26–Mar 12 (sow outdoors) | Sep 15–29 (sowing) |
| Arugula | – | Feb 26–Mar 26 (sow outdoors) | Sep 15–Oct 13 (sowing) |
| Mustard greens | – | Feb 26–Mar 19 (sow outdoors) | Sep 15–29 (sowing) |
| Swiss chard | Feb 12–26 | Mar 12–Apr 2 (transplant) Mar 12–Apr 9 (sow outdoors) | Sep 1–15 (sowing) |
| Beet | – | Feb 26–Mar 26 (sow outdoors) | Sep 1–15 (sowing) |
| Carrot | – | Mar 5–Apr 2 (sow outdoors) | Aug 18–Sep 1 (sowing) |
| Radish | – | Feb 19–Apr 2 (sow outdoors) | Sep 29–Oct 13 (sowing) |
| Turnip | – | Feb 26–Mar 19 (sow outdoors) | Sep 1–15 (sowing) |
| Parsnip | – | Mar 5–26 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Jan 29–Feb 26 (sow outdoors) | Aug 18–Sep 1 (sowing) |
| Onion (bulbing) | Jan 1–15 | Feb 12–26 (transplant) | – |
| Green onion / scallion | – | Feb 12–Mar 12 (sow outdoors) | Sep 1–15 (sowing) |
| Leek | Jan 1–15 | Feb 26–Mar 12 (transplant) | – |
| Garlic | – | – | Sep 29–Oct 27 (sowing) |
| Shallot | – | Feb 12–26 (transplant) | Sep 29–Oct 27 (sowing) |
| Potato | – | Feb 26–Mar 12 (transplant) | Jul 21–Aug 4 (transplant) |
| Sweet potato | – | Apr 16–30 (transplant) | – |
| Sweet corn | – | Apr 2–16 (sow outdoors) | – |
| Bean, bush (snap) | – | Apr 2–16 (sow outdoors) | Aug 18–Sep 1 (sowing) |
| Bean, pole | – | Apr 2–16 (sow outdoors) | – |
| Lima bean | – | Apr 9–23 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Apr 16–May 7 (sow outdoors) | – |
| Cucumber | Feb 26–Mar 5 | Apr 2–16 (transplant) Apr 2–16 (sow outdoors) | Aug 18–Sep 1 (sowing) |
| Summer squash / zucchini | Feb 26–Mar 5 | Apr 2–16 (transplant) Apr 2–16 (sow outdoors) | Aug 18–Sep 1 (sowing) |
| Winter squash | Feb 26–Mar 5 | Apr 2–16 (transplant) Apr 2–16 (sow outdoors) | – |
| Pumpkin | – | Apr 2–16 (sow outdoors) | – |
| Watermelon | Feb 26–Mar 5 | Apr 9–23 (transplant) Apr 9–23 (sow outdoors) | – |
| Cantaloupe / muskmelon | Feb 26–Mar 5 | Apr 9–23 (transplant) Apr 9–23 (sow outdoors) | – |
| Okra | Feb 12–26 | Apr 9–23 (transplant) Apr 9–23 (sow outdoors) | – |
| Celery | Jan 1–15 | Apr 2–9 (transplant) | – |
| Basil | Feb 12–26 | Apr 2–16 (transplant) Apr 2–16 (sow outdoors) | – |
| Cilantro | – | Mar 12–Apr 9 (sow outdoors) | Sep 15–29 (sowing) |
| Parsley | Jan 15–29 | Mar 12–26 (transplant) Mar 5–26 (sow outdoors) | – |
| Dill | – | Mar 26–Apr 9 (sow outdoors) | Sep 15–29 (sowing) |
| Sunflower | – | Mar 26–Apr 9 (sow outdoors) | – |
| Asparagus (crowns) | – | Feb 26–Mar 12 (transplant) | – |
| Rhubarb (crowns) | – | Feb 26–Mar 12 (transplant) | – |
| Strawberry (plants) | – | Feb 26–Mar 12 (transplant) | Sep 1–29 (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: Friday Harbor AP, WA (NOAA GHCN-Daily ID USW00094276), elevation 109 ft, 3.6 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Olga 2 SE, WA | 13 mi | Feb 26 | Nov 29 |
| Anacortes, WA | 22 mi | Mar 8 | Nov 20 |
| Whidbey Island NAS, WA | 24 mi | Mar 13 | Nov 14 |
The average last-frost dates of these stations span 31 days, a rough guide to local variation. See data sources & methods.
Frost questions for 98250
When is the last frost in 98250?
The average (50% chance) last spring freeze of 32°F for ZIP 98250 is March 26. For a more cautious planting date, use April 21, when only 1 year in 10 still sees a later freeze.
When is the first frost in 98250?
The average first fall freeze is November 10. In 1 year in 10 it comes by October 21.
What hardiness zone is 98250?
ZIP 98250 is in USDA zone 9a (20 to 25°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 98250 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
98243 98286 98280 98261 98297 98245 98222 98279
Other ZIP codes in San Juan County
98222 98243 98245 98261 98279 98280 98286 98297 All San Juan County frost dates · Washington frost dates
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Weekly yard timing, plus frost and soil-temperature alerts for your ZIP code.
- Freeze alerts
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- Weekly yard to-dos
Free. One weekly email plus alerts when your ZIP has a frost or a soil-temperature change worth acting on. After you submit, Kit (our email provider) sends a confirmation email: check your email and click the link to confirm. You aren't subscribed until you do. We collect only your email address and ZIP, sent to Kit to deliver The Dial. Unsubscribe anytime.