What USDA hardiness zone is Island County, Washington?

Every ZIP code in Island County, Washington is USDA hardiness zone 8b, from the USDA 2023 Plant Hardiness Zone Map.

When is the last spring frost in Island County, Washington?

The median last spring freeze runs March 1 – March 17 across the 4 NOAA weather stations serving Island County, Washington, from NOAA 1991-2020 Climate Normals. Half of years freeze later than the median.

Washington

Planting zones in Island County, Washington

Every ZIP code in this county is USDA zone 8b — so unlike most of the places people look up, there is one right answer here and it holds wherever you are in the county.

USDA zone 8b The same in all 8 ZIP codes

ZIP codes 8 8 have a NOAA station within range

Weather stations 4 NOAA 1991–2020 normals, across 208 sq mi

Your ZIP code

Get the exact answer for your address

Everything above describes Island County, Washington as a whole. Hardiness zones and freeze dates are published per ZIP code, so yours is exact — enter it and this page will tell you your zone, which NOAA station it comes from and how far away that station is.

What you can sow in Island County now

6 of 32 crops that every one of the 4 NOAA stations serving this county agrees still has time to mature — with a week in hand, so this holds until the page is next rebuilt.

🌱 Radishes 28d
🥬 Arugula 35d
🥬 Baby Salad Greens 35d
🥬 Spinach 40d
🥬 Mustard Greens 40d
🥔 Turnips 50d

Counted against a first fall freeze of November 11 – November 28 across 4 of those stations, NOAA 1991–2020 normals.

A further 7 crops depend on where in Island County you are — its stations disagree about them. The ZIP lookup above settles it for one address.

All 4 stations agreeAt least one station

Every one of the 4 NOAA stations serving this county counts March 17 – November 11 as growing season (239 days). Widening to any single station gives March 1 – November 28 (272 days).

That is a 33-day difference inside one county — which is why this page gives ranges rather than a single planting date. The ZIP lookup above resolves it to one station.

Your freeze dates

Last spring freeze March 1 – March 17

First fall freeze November 11 – November 28

Across the 4 NOAA stations serving this county. These are medians — half of years freeze later than the date shown — so treat the later end of each range as the cautious one.

The growing season runs 237–274 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 68.2–71.2 °F in June–August. Summer rain over the same months runs 2.6–3.7" across those 4 stations, against the rough inch a week — about 13 inches over the same 92 days — that a vegetable garden is usually reckoned to want. The middle station covers about 21% of it, so a summer garden here is watered rather than rained on. The inches are NOAA's published normals; the inch a week is a rule of thumb, and it takes no account of a 71 °F summer afternoon drying the soil faster than a cool one.

Every ZIP code in Island County

Zones are published per ZIP code, not per county, so this is the exact answer rather than the county's average. The station column is the nearest one to that ZIP code's centroid and how far away it is — the same figure the tools use, shown here so you can see which ZIP codes are well covered and which are reaching.

ZIP code	USDA zone	Nearest NOAA station	Distance
98236	8b	Everett Snohomish AP, WA	10.9 km
98239	8b	Coupeville 1 S, WA	2.9 km
98249	8b	Port Townsend, WA	19.6 km
98253	8b	Port Townsend, WA	14.3 km
98260	8b	Everett Snohomish AP, WA	19.2 km
98277	8b	Whidbey Island Nas, WA	4.3 km
98278	8b	Whidbey Island Nas, WA	1.2 km
98282	8b	Coupeville 1 S, WA	14.3 km

ZIP-code positions are area centroids, so a large rural ZIP code's listed distance is measured from the middle of its area rather than from any particular address in it.

When to start seeds in Island County

Every date below is anchored on the last spring freeze at each station and reported as a range across all 4 of them, because no one station speaks for the county.

Crop	Job	When	Offset
🧅 Green Onions	Start indoors	January 4 – January 20	8 wk before
🌶️ Peppers	Start indoors	January 4 – January 20	8 wk before
🥦 Broccoli	Start indoors	January 18 – February 3	6 wk before
🥬 Cabbage	Start indoors	January 18 – February 3	6 wk before
🥬 Collards	Start indoors	January 18 – February 3	6 wk before
🥬 Kale	Start indoors	January 18 – February 3	6 wk before
🥬 Leaf Lettuce	Start indoors	January 18 – February 3	6 wk before
🫛 Peas	Direct sow	January 18 – February 3	6 wk before
🥬 Spinach	Direct sow	January 18 – February 3	6 wk before
🍠 Sweet Potato	Start indoors	January 18 – February 3	6 wk before
🍅 Tomatoes	Start indoors	January 18 – February 3	6 wk before
🥬 Bok Choy	Start indoors	January 25 – February 10	5 wk before
🥬 Kohlrabi	Start indoors	January 25 – February 10	5 wk before
🥬 Swiss Chard	Start indoors	January 25 – February 10	5 wk before
🥬 Arugula	Direct sow	February 1 – February 17	4 wk before
🥬 Baby Salad Greens	Direct sow	February 1 – February 17	4 wk before
🥕 Beets	Direct sow	February 1 – February 17	4 wk before
🧅 Green Onions	Direct sow	February 1 – February 17	4 wk before
🥬 Mustard Greens	Direct sow	February 1 – February 17	4 wk before
🌶️ Okra	Start indoors	February 1 – February 17	4 wk before
🌱 Radishes	Direct sow	February 1 – February 17	4 wk before
🥔 Turnips	Direct sow	February 1 – February 17	4 wk before
🥬 Cabbage	Set out	February 8 – February 24	3 wk before
🥕 Carrots	Direct sow	February 8 – February 24	3 wk before
🥬 Collards	Direct sow	February 8 – February 24	3 wk before
🥬 Collards	Set out	February 8 – February 24	3 wk before
🥒 Cucumbers	Start indoors	February 8 – February 24	3 wk before
🧅 Green Onions	Set out	February 8 – February 24	3 wk before
🥬 Kale	Direct sow	February 8 – February 24	3 wk before
🥬 Kale	Set out	February 8 – February 24	3 wk before
🥬 Kohlrabi	Direct sow	February 8 – February 24	3 wk before
🥬 Kohlrabi	Set out	February 8 – February 24	3 wk before
🥬 Leaf Lettuce	Direct sow	February 8 – February 24	3 wk before
🎃 Pumpkins	Start indoors	February 8 – February 24	3 wk before
🎃 Summer Squash	Start indoors	February 8 – February 24	3 wk before
🎃 Winter Squash	Start indoors	February 8 – February 24	3 wk before
🥒 Zucchini	Start indoors	February 8 – February 24	3 wk before
🥬 Bok Choy	Direct sow	February 15 – March 3	2 wk before
🥬 Bok Choy	Set out	February 15 – March 3	2 wk before
🥦 Broccoli	Set out	February 15 – March 3	2 wk before
🌿 Cilantro	Direct sow	February 15 – March 3	2 wk before
🥬 Leaf Lettuce	Set out	February 15 – March 3	2 wk before
🥬 Swiss Chard	Direct sow	February 15 – March 3	2 wk before
🥬 Swiss Chard	Set out	February 15 – March 3	2 wk before
🌿 Dill	Direct sow	February 22 – March 10	1 wk before
🫘 Bush Beans	Direct sow	March 8 – March 24	1 wk after
🥒 Cucumbers	Set out	March 8 – March 24	1 wk after
🎃 Pumpkins	Direct sow	March 8 – March 24	1 wk after
🎃 Pumpkins	Set out	March 8 – March 24	1 wk after
🎃 Summer Squash	Direct sow	March 8 – March 24	1 wk after
🎃 Summer Squash	Set out	March 8 – March 24	1 wk after
🌽 Sweet Corn	Direct sow	March 8 – March 24	1 wk after
🍅 Tomatoes	Set out	March 8 – March 24	1 wk after
🎃 Winter Squash	Direct sow	March 8 – March 24	1 wk after
🎃 Winter Squash	Set out	March 8 – March 24	1 wk after
🥒 Zucchini	Direct sow	March 8 – March 24	1 wk after
🥒 Zucchini	Set out	March 8 – March 24	1 wk after
🥒 Cucumbers	Direct sow	March 15 – March 31	2 wk after
🌶️ Okra	Direct sow	March 15 – March 31	2 wk after
🌶️ Okra	Set out	March 15 – March 31	2 wk after
🌶️ Peppers	Set out	March 15 – March 31	2 wk after
🫘 Southern Peas	Direct sow	March 15 – March 31	2 wk after
🍠 Sweet Potato	Set out	March 15 – March 31	2 wk after

Offsets are published guidance; the dates they land on are computed from measured NOAA normals. The seed-starting tool does this for your own ZIP code and counts the days.

What lives through a zone 8b winter

Of 74 perennial edibles, 54 come through a zone 8b winter — and 11 fail here for being too warm rather than too cold, needing more winter chill than this county gets or more heat than they tolerate. Among the ones that work: Apple, Aronia, Elderberry, Asparagus, Horseradish, Sunchoke, Walking Onion, Chives.

Hardiness ranges are a judgement, published by growers rather than measured; the zone they are compared against is measured. On a warm-end verdict, check with your local extension service — a coastal zone 8 and an inland zone 8 are not the same summer.

Cautious — shortens the seasonMedian across stationsOptimistic

Last spring freeze: Plan to April 3 to be careful. Median March 1 – March 17 across 4 stations; February 3 is the optimistic end.
First fall freeze: Plan to October 21 to be careful. Median November 11 – November 28 across 4 stations; December 26 is the optimistic end.

NOAA publishes these as probabilities, not averages — the middle figure is a median, so half of years fall either side of it. The cautious end is the 10% tail: in roughly nine years in ten the freeze falls on the safe side of it.

The 4 stations behind these numbers

All 4 NOAA stations whose normals this page quotes, spanning about 49 km north to south. Every one is named with its identifier in the station list below — this page does not single one out, because no one station speaks for a whole county.

A relative sketch, not a map with a projection: longitude is adjusted for latitude so the shape is not stretched, and there is no basemap. For the one station nearest a specific address, with its real distance, use the ZIP lookup above.

These are the stations this county's ZIP codes actually cite as nearest — not a claim that each one sits inside its boundary, since a rural ZIP legitimately reaches over it. Every figure above comes from them, and each is named so you can check it.

Station	NOAA ID	Last spring freeze	First fall freeze	Season
Coupeville 1 S, WA	USC00451783	March 17	November 11	237 days
Everett Snohomish AP, WA	USW00024222	March 9	November 17	250 days
Port Townsend, WA	USC00456678	March 1	November 28	274 days
Whidbey Island Nas, WA	USW00024255	March 13	November 14	244 days

These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.

Your own ZIP

Work out your own dates

This page describes a whole county. Every tool below answers for one ZIP code, which is the grain the underlying data is published at.

Other places to compare

Island County sits in Washington. That page carries the whole state's zone spread, its metro areas, and every other county in it with a page here.

More of Washington

Counties with the same zones — 8b

Matched on the exact zone set, not a dominant zone, so the winter answer on these pages really is the same one as here.

Gear

If you want to act on this

Each link opens an Amazon search rather than a product we picked. We have not tested these and do not rank them — the search is the honest version, and you choose.

Row cover and frost clothThe season here closes at the first fall freeze dated above — a cover buys back some of those days at the end.

As an Amazon Associate we earn from qualifying purchases. That costs you nothing extra, and it buys no influence over anything on this site: the dates come from NOAA normals and the zones from the USDA, and no product affects either.

Sources

Where these numbers come from

Hardiness zones are the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. Freeze dates and growing-season lengths are NOAA 1991–2020 Climate Normals, taken per station and cited above by name and NOAA ID.

County boundaries come from the Census ZCTA-to-county relation, which is what places each ZIP code — and which treats parishes, boroughs and census areas as county equivalents. No station is chosen to represent this county: every range above is taken across all of them and the count is stated, because picking one would be a judgement dressed as a measurement.