Fall in zone 9aPhoto: George Chernilevsky, Public domain, via Wikimedia Commons
Frost dates for ZIP 98280 (San Juan County, 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, Olga 2 SE, WA (3 miles away).
- Average last spring frostFeb 2650% chance of a 32°F freeze after this date
- Average first fall frostNov 2950% chance of a 32°F freeze by this date
- Growing season (frost-free)276 daysmedian, 32°F threshold
- USDA hardiness zone9a20 to 25°F avg. coldest night
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Frost and freeze alerts from the NWS forecast for 98280, the spring soil-temperature heads-up for pre-emergent, and a short weekly yard-timing email.
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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 98280 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
- Lettuce: fall sowing Sep 20–Oct 18
- Lettuce: fall transplant Oct 4–25
- Spinach: fall sowing Oct 4–25
- Bok choy / Asian greens: fall sowing Oct 4–18
- Arugula: fall sowing Oct 4–Nov 1
- Mustard greens: fall sowing Oct 4–18
- Radish: fall sowing Oct 18–Nov 1
- Garlic: fall sowing Oct 18–Nov 15
- Shallot: fall sowing Oct 18–Nov 15
- Cilantro: fall sowing Oct 4–18
- Dill: fall sowing Oct 4–18
- Strawberry (plants): fall transplant Sep 20–Oct 18
Prune now
No frost-timed pruning windows are open this week.
Your average first frost is Nov 29: 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) | Jan 23 |
| 50% (the "average" last frost) | Feb 26 |
| 10% (cautious: only 1 year in 10 freezes later) | Mar 23 |
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) | Nov 10 |
| 50% (the "average" first frost) | Nov 29 |
| 90% (late: most years have frozen by now) | Dec 23 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Mar 29 | Nov 10 |
| 32°F (freeze) | Feb 26 | Nov 29 |
| 28°F (hard freeze) | Jan 26 | Dec 14 |
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 98280
Dates count from your average last spring frost (Feb 26) and first fall frost (Nov 29). 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 1–15 | Mar 5–19 (transplant) | Aug 2–30 (transplant) |
| Pepper (sweet and hot) | Dec 18–Jan 1 | Mar 12–26 (transplant) | Aug 9–30 (transplant) |
| Eggplant | Dec 18–Jan 1 | Mar 12–26 (transplant) | Aug 9–30 (transplant) |
| Tomatillo | Jan 1–15 | Mar 5–19 (transplant) | – |
| Lettuce | Jan 1–15 | Feb 5–26 (transplant) Jan 29–Mar 12 (sow outdoors) | Oct 4–25 (transplant) Sep 20–Oct 18 (sowing) |
| Spinach | – | Jan 15–Feb 5 (sow outdoors) | Oct 4–25 (sowing) |
| Kale | Jan 1–15 | Jan 29–Feb 12 (transplant) Jan 29–Feb 12 (sow outdoors) | Sep 6–Oct 4 (transplant) Aug 23–Sep 20 (sowing) |
| Collards | Jan 1–15 | Jan 29–Feb 26 (transplant) Jan 29–Feb 26 (sow outdoors) | Sep 6–Oct 4 (transplant) Aug 23–Sep 20 (sowing) |
| Broccoli | Dec 18–Jan 1 | Jan 29–Feb 12 (transplant) | Aug 23–Sep 20 (transplant) |
| Cabbage | Dec 18–Jan 1 | Jan 29–Feb 12 (transplant) | Aug 23–Sep 20 (transplant) |
| Cauliflower | Dec 18–Jan 1 | Feb 12–26 (transplant) | Aug 23–Sep 20 (transplant) |
| Brussels sprouts | Dec 4–18 | Jan 29–Feb 12 (transplant) | Aug 9–30 (transplant) |
| Kohlrabi | Jan 1–15 | Jan 29–Feb 12 (transplant) Jan 29–Feb 12 (sow outdoors) | Sep 20–Oct 4 (sowing) |
| Bok choy / Asian greens | – | Jan 29–Feb 12 (sow outdoors) | Oct 4–18 (sowing) |
| Arugula | – | Jan 29–Feb 26 (sow outdoors) | Oct 4–Nov 1 (sowing) |
| Mustard greens | – | Jan 29–Feb 19 (sow outdoors) | Oct 4–18 (sowing) |
| Swiss chard | Jan 15–29 | Feb 12–Mar 5 (transplant) Feb 12–Mar 12 (sow outdoors) | Sep 20–Oct 4 (sowing) |
| Beet | – | Jan 29–Feb 26 (sow outdoors) | Sep 20–Oct 4 (sowing) |
| Carrot | – | Feb 5–Mar 5 (sow outdoors) | Sep 6–20 (sowing) |
| Radish | – | Jan 22–Mar 5 (sow outdoors) | Oct 18–Nov 1 (sowing) |
| Turnip | – | Jan 29–Feb 19 (sow outdoors) | Sep 20–Oct 4 (sowing) |
| Parsnip | – | Feb 5–26 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Jan 1–29 (sow outdoors) | Sep 6–20 (sowing) |
| Onion (bulbing) | Dec 4–18 | Jan 15–29 (transplant) | – |
| Green onion / scallion | – | Jan 15–Feb 12 (sow outdoors) | Sep 20–Oct 4 (sowing) |
| Leek | Dec 4–18 | Jan 29–Feb 12 (transplant) | – |
| Garlic | – | – | Oct 18–Nov 15 (sowing) |
| Shallot | – | Jan 15–29 (transplant) | Oct 18–Nov 15 (sowing) |
| Potato | – | Jan 29–Feb 12 (transplant) | Aug 9–23 (transplant) |
| Sweet potato | – | Mar 19–Apr 2 (transplant) | – |
| Sweet corn | – | Mar 5–19 (sow outdoors) | – |
| Bean, bush (snap) | – | Mar 5–19 (sow outdoors) | Sep 6–20 (sowing) |
| Bean, pole | – | Mar 5–19 (sow outdoors) | – |
| Lima bean | – | Mar 12–26 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Mar 19–Apr 9 (sow outdoors) | – |
| Cucumber | Jan 29–Feb 5 | Mar 5–19 (transplant) Mar 5–19 (sow outdoors) | Sep 6–20 (sowing) |
| Summer squash / zucchini | Jan 29–Feb 5 | Mar 5–19 (transplant) Mar 5–19 (sow outdoors) | Sep 6–20 (sowing) |
| Winter squash | Jan 29–Feb 5 | Mar 5–19 (transplant) Mar 5–19 (sow outdoors) | – |
| Pumpkin | – | Mar 5–19 (sow outdoors) | – |
| Watermelon | Jan 29–Feb 5 | Mar 12–26 (transplant) Mar 12–26 (sow outdoors) | – |
| Cantaloupe / muskmelon | Jan 29–Feb 5 | Mar 12–26 (transplant) Mar 12–26 (sow outdoors) | – |
| Okra | Jan 15–29 | Mar 12–26 (transplant) Mar 12–26 (sow outdoors) | – |
| Celery | Dec 4–18 | Mar 5–12 (transplant) | – |
| Basil | Jan 15–29 | Mar 5–19 (transplant) Mar 5–19 (sow outdoors) | – |
| Cilantro | – | Feb 12–Mar 12 (sow outdoors) | Oct 4–18 (sowing) |
| Parsley | Dec 18–Jan 1 | Feb 12–26 (transplant) Feb 5–26 (sow outdoors) | – |
| Dill | – | Feb 26–Mar 12 (sow outdoors) | Oct 4–18 (sowing) |
| Sunflower | – | Feb 26–Mar 12 (sow outdoors) | – |
| Asparagus (crowns) | – | Jan 29–Feb 12 (transplant) | – |
| Rhubarb (crowns) | – | Jan 29–Feb 12 (transplant) | – |
| Strawberry (plants) | – | Jan 29–Feb 12 (transplant) | Sep 20–Oct 18 (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: Olga 2 SE, WA (NOAA GHCN-Daily ID USC00456096), elevation 80 ft, 3.4 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Friday Harbor AP, WA | 8 mi | Mar 26 | Nov 10 |
| Anacortes, WA | 13 mi | Mar 8 | Nov 20 |
| Bellingham 3 SSW, WA | 19 mi | Apr 1 | Nov 2 |
The average last-frost dates of these stations span 37 days, a rough guide to local variation. See data sources & methods.
Frost questions for 98280
When is the last frost in 98280?
The average (50% chance) last spring freeze of 32°F for ZIP 98280 is February 26. For a more cautious planting date, use March 23, when only 1 year in 10 still sees a later freeze.
When is the first frost in 98280?
The average first fall freeze is November 29. In 1 year in 10 it comes by November 10.
What hardiness zone is 98280?
ZIP 98280 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 98280 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
98222 98279 98286 98245 98243 98261 98250 Roche Harbor 98297
Other ZIP codes in San Juan County
98222 98243 98245 98250 98261 98279 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.