Fall in zone 8bPhoto: George Chernilevsky, Public domain, via Wikimedia Commons
Frost dates for ZIP 98278 (Whidbey Island Station, 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, Whidbey Island NAS, WA (1 miles away).
- Average last spring frostMar 1350% chance of a 32°F freeze after this date
- Average first fall frostNov 1450% chance of a 32°F freeze by this date
- Growing season (frost-free)244 daysmedian, 32°F threshold
- USDA hardiness zone8b15 to 20°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
50°F 50–55°F
24-hour average · latest 50°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Darrington 21 NNE (58 mi).
4-inch depth
50°F 50–55°F
24-hour average · latest 50°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Darrington 21 NNE (58 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 98278 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 50°F at 4 inches (estimated soil temperature, not a station reading). Fall pre-emergent window is mostly past. Next: spring, when soil reaches 50°F (typically 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 14: 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 20 |
| 50% (the "average" last frost) | Mar 13 |
| 10% (cautious: only 1 year in 10 freezes later) | Apr 1 |
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 26 |
| 50% (the "average" first frost) | Nov 14 |
| 90% (late: most years have frozen by now) | Dec 5 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Apr 9 | Oct 28 |
| 32°F (freeze) | Mar 13 | Nov 14 |
| 28°F (hard freeze) | Feb 18 | 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 98278
Dates count from your average last spring frost (Mar 13) and first fall frost (Nov 14). 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 16–30 | Mar 20–Apr 3 (transplant) | Jul 18–Aug 15 (transplant) |
| Pepper (sweet and hot) | Jan 2–16 | Mar 27–Apr 10 (transplant) | Jul 25–Aug 15 (transplant) |
| Eggplant | Jan 2–16 | Mar 27–Apr 10 (transplant) | Jul 25–Aug 15 (transplant) |
| Tomatillo | Jan 16–30 | Mar 20–Apr 3 (transplant) | – |
| Lettuce | Jan 16–30 | Feb 20–Mar 13 (transplant) Feb 13–Mar 27 (sow outdoors) | Sep 19–Oct 10 (transplant) Sep 5–Oct 3 (sowing) |
| Spinach | – | Jan 30–Feb 20 (sow outdoors) | Sep 19–Oct 10 (sowing) |
| Kale | Jan 16–30 | Feb 13–27 (transplant) Feb 13–27 (sow outdoors) | Aug 22–Sep 19 (transplant) Aug 8–Sep 5 (sowing) |
| Collards | Jan 16–30 | Feb 13–Mar 13 (transplant) Feb 13–Mar 13 (sow outdoors) | Aug 22–Sep 19 (transplant) Aug 8–Sep 5 (sowing) |
| Broccoli | Jan 2–16 | Feb 13–27 (transplant) | Aug 8–Sep 5 (transplant) |
| Cabbage | Jan 2–16 | Feb 13–27 (transplant) | Aug 8–Sep 5 (transplant) |
| Cauliflower | Jan 2–16 | Feb 27–Mar 13 (transplant) | Aug 8–Sep 5 (transplant) |
| Brussels sprouts | Dec 19–Jan 2 | Feb 13–27 (transplant) | Jul 25–Aug 15 (transplant) |
| Kohlrabi | Jan 16–30 | Feb 13–27 (transplant) Feb 13–27 (sow outdoors) | Sep 5–19 (sowing) |
| Bok choy / Asian greens | – | Feb 13–27 (sow outdoors) | Sep 19–Oct 3 (sowing) |
| Arugula | – | Feb 13–Mar 13 (sow outdoors) | Sep 19–Oct 17 (sowing) |
| Mustard greens | – | Feb 13–Mar 6 (sow outdoors) | Sep 19–Oct 3 (sowing) |
| Swiss chard | Jan 30–Feb 13 | Feb 27–Mar 20 (transplant) Feb 27–Mar 27 (sow outdoors) | Sep 5–19 (sowing) |
| Beet | – | Feb 13–Mar 13 (sow outdoors) | Sep 5–19 (sowing) |
| Carrot | – | Feb 20–Mar 20 (sow outdoors) | Aug 22–Sep 5 (sowing) |
| Radish | – | Feb 6–Mar 20 (sow outdoors) | Oct 3–17 (sowing) |
| Turnip | – | Feb 13–Mar 6 (sow outdoors) | Sep 5–19 (sowing) |
| Parsnip | – | Feb 20–Mar 13 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Jan 16–Feb 13 (sow outdoors) | Aug 22–Sep 5 (sowing) |
| Onion (bulbing) | Dec 19–Jan 2 | Jan 30–Feb 13 (transplant) | – |
| Green onion / scallion | – | Jan 30–Feb 27 (sow outdoors) | Sep 5–19 (sowing) |
| Leek | Dec 19–Jan 2 | Feb 13–27 (transplant) | – |
| Garlic | – | – | Oct 3–31 (sowing) |
| Shallot | – | Jan 30–Feb 13 (transplant) | Oct 3–31 (sowing) |
| Potato | – | Feb 13–27 (transplant) | Jul 25–Aug 8 (transplant) |
| Sweet potato | – | Apr 3–17 (transplant) | – |
| Sweet corn | – | Mar 20–Apr 3 (sow outdoors) | – |
| Bean, bush (snap) | – | Mar 20–Apr 3 (sow outdoors) | Aug 22–Sep 5 (sowing) |
| Bean, pole | – | Mar 20–Apr 3 (sow outdoors) | – |
| Lima bean | – | Mar 27–Apr 10 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Apr 3–24 (sow outdoors) | – |
| Cucumber | Feb 13–20 | Mar 20–Apr 3 (transplant) Mar 20–Apr 3 (sow outdoors) | Aug 22–Sep 5 (sowing) |
| Summer squash / zucchini | Feb 13–20 | Mar 20–Apr 3 (transplant) Mar 20–Apr 3 (sow outdoors) | Aug 22–Sep 5 (sowing) |
| Winter squash | Feb 13–20 | Mar 20–Apr 3 (transplant) Mar 20–Apr 3 (sow outdoors) | – |
| Pumpkin | – | Mar 20–Apr 3 (sow outdoors) | – |
| Watermelon | Feb 13–20 | Mar 27–Apr 10 (transplant) Mar 27–Apr 10 (sow outdoors) | – |
| Cantaloupe / muskmelon | Feb 13–20 | Mar 27–Apr 10 (transplant) Mar 27–Apr 10 (sow outdoors) | – |
| Okra | Jan 30–Feb 13 | Mar 27–Apr 10 (transplant) Mar 27–Apr 10 (sow outdoors) | – |
| Celery | Dec 19–Jan 2 | Mar 20–27 (transplant) | – |
| Basil | Jan 30–Feb 13 | Mar 20–Apr 3 (transplant) Mar 20–Apr 3 (sow outdoors) | – |
| Cilantro | – | Feb 27–Mar 27 (sow outdoors) | Sep 19–Oct 3 (sowing) |
| Parsley | Jan 2–16 | Feb 27–Mar 13 (transplant) Feb 20–Mar 13 (sow outdoors) | – |
| Dill | – | Mar 13–27 (sow outdoors) | Sep 19–Oct 3 (sowing) |
| Sunflower | – | Mar 13–27 (sow outdoors) | – |
| Asparagus (crowns) | – | Feb 13–27 (transplant) | – |
| Rhubarb (crowns) | – | Feb 13–27 (transplant) | – |
| Strawberry (plants) | – | Feb 13–27 (transplant) | Sep 5–Oct 3 (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: Whidbey Island NAS, WA (NOAA GHCN-Daily ID USW00024255), elevation 47 ft, 0.7 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Coupeville 1 S, WA | 9 mi | Mar 17 | Nov 11 |
| Anacortes, WA | 12 mi | Mar 8 | Nov 20 |
| Mt Vernon 3 WNW, WA | 15 mi | Mar 24 | Nov 3 |
The average last-frost dates of these stations span 16 days, a rough guide to local variation. See data sources & methods.
Frost questions for 98278
When is the last frost in 98278?
The average (50% chance) last spring freeze of 32°F for ZIP 98278 is March 13. For a more cautious planting date, use April 1, when only 1 year in 10 still sees a later freeze.
When is the first frost in 98278?
The average first fall freeze is November 14. In 1 year in 10 it comes by October 26.
What hardiness zone is 98278?
ZIP 98278 is in USDA zone 8b (15 to 20°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 98278 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
98277 Oak Harbor 98221 Anacortes 98257 La Conner 98239 Coupeville 98282 Camano 98261 98273 Mount Vernon 98238 Conway
Other ZIP codes in Island County
98236 98239 98249 98253 98260 98277 98282 All Island County frost dates · Washington frost dates
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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.