California
Planting zones in Humboldt County, California
This county spans USDA zones 9a to 9b, so there is no single zone for Humboldt County and anyone who gives you one is rounding. 74% of its ZIP codes are zone 9b; the rest are not.
Your ZIP code
Get the exact answer for your address
Everything above describes Humboldt County, California 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.
Humboldt County does not have one planting answer
Its own weather stations disagree about 28 of the 32 crops in this table right now, so any single list would be wrong for part of the county. That is not a gap in the data — it is what the data says.
- Shortest season
- 209 days
ORICK PRAIRIE CREEK PARK, CA US (USC00046498) - Longest season
- 365 days
SHELTER COVE AVIATION, CA US (USC00048163)
156 days of growing season separate those two stations, and both serve ZIP codes in Humboldt County. The ZIP lookup above answers for one address instead of averaging a place that has no average.
Why the hardiness zone does not settle this
A USDA zone is a winter-minimum statistic. It was never a growing-season one, and it does not behave like one: within a single zone the growing season runs a median 54 days wider at the 10th–90th percentile, and annual growing degree days vary by 2.02×.
The zones also overlap rather than stack — 30% of zone 6b freezes before the median zone 6a station. The zone tells you what survives your winter; the station tells you what finishes before your autumn.
The growing season at one or more of this county's stations crosses 1 January, so a one-year bar would have to start the season after it ended. No chart is drawn rather than a misleading one.
Which zone you are in depends where you are
Humboldt County covers 2 hardiness zones. A guide that gives the county one zone has picked whichever is largest and rounded everyone else into it — fine for the 74% in zone 9b and wrong for the other 26%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 9b | 26 | 74% | |
| 9a | 9 | 26% |
Zones are published per ZIP code, so yours is exact even though the county's is not. The hardiness tool will tell you which one you are in.
Your freeze dates
No freeze range is given for Humboldt County, because at least one station here records no freeze at any probability, so there is no date to average. The countdown tool answers per ZIP code, where the question has a definite answer.
The growing season runs 209–365 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 63–88.7 °F in June–August. Summer rain over the same months runs 0.8–1.4" across those 6 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 8% 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 70 °F summer afternoon drying the soil faster than a cool one.
Every ZIP code in Humboldt 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 |
|---|---|---|---|
| 95501 | 9b | Eureka Wfo Woodley Island, CA | 1.6 km |
| 95503 | 9b | Eureka Wfo Woodley Island, CA | 9.1 km |
| 95511 | 9a | Richardson Gr SP, CA | 23.6 km |
| 95514 | 9a | Grizzly Creek SP, CA | 30.5 km |
| 95519 | 9b | Arcata Eureka AP, CA | 5.0 km |
| 95521 | 9b | Eureka Wfo Woodley Island, CA | 10.4 km |
| 95524 | 9b | Eureka Wfo Woodley Island, CA | 9.4 km |
| 95525 | 9a | Arcata Eureka AP, CA | 24.0 km |
| 95526 | 9a | Grizzly Creek SP, CA | 19.9 km |
| 95528 | 9b | Grizzly Creek SP, CA | 2.2 km |
| 95536 | 9b | Scotia, CA | 9.2 km |
| 95537 | 9b | Eureka Wfo Woodley Island, CA | 10.4 km |
| 95540 | 9b | Scotia, CA | 9.5 km |
| 95542 | 9a | Richardson Gr SP, CA | 8.0 km |
| 95545 | 9b | Scotia, CA | 24.7 km |
| 95546 | 9a | Orleans, CA | 21.6 km |
| 95547 | 9b | Scotia, CA | 9.8 km |
| 95549 | 9b | Grizzly Creek SP, CA | 20.0 km |
| 95550 | 9b | Eureka Wfo Woodley Island, CA | 27.5 km |
| 95551 | 9b | Eureka Wfo Woodley Island, CA | 16.1 km |
| 95553 | 9b | Richardson Gr SP, CA | 23.7 km |
| 95554 | 9b | Grizzly Creek SP, CA | 23.9 km |
| 95555 | 9b | Orick Prairie Creek Park, CA | 7.5 km |
| 95556 | 9a | Orleans, CA | 4.7 km |
| 95558 | 9b | Scotia, CA | 21.0 km |
| 95559 | 9a | Richardson Gr SP, CA | 18.6 km |
| 95560 | 9b | Richardson Gr SP, CA | 13.5 km |
| 95562 | 9b | Scotia, CA | 4.7 km |
| 95564 | 9b | Eureka Wfo Woodley Island, CA | 4.3 km |
| 95565 | 9b | Scotia, CA | 8.1 km |
| 95569 | 9b | Grizzly Creek SP, CA | 14.5 km |
| 95570 | 9b | Arcata Eureka AP, CA | 15.2 km |
| 95571 | 9b | Grizzly Creek SP, CA | 13.8 km |
| 95573 | 9a | Arcata Eureka AP, CA | 37.6 km |
| 95589 | 9b | Shelter Cove Aviation, CA | 8.5 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.
What survives the winter changes across Humboldt County
Zone 9a carries 46 of 74 perennial edibles; zone 9b carries 40. The best number is not always the warmest zone — the count peaks in the middle and falls both ways, because the warm end loses plants to insufficient winter chill and summer heat, not to cold.
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.
At least one station here freezes across the new year, which puts the two ends of a spread on opposite sides of the calendar. Drawing it would produce a bar spanning almost the whole year and meaning nothing, so none is drawn.
The 8 stations behind these numbers
All 8 NOAA stations whose normals this page quotes, spanning about 148 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 |
|---|---|---|---|---|
| Arcata Eureka AP, CA | USW00024283 | March 8 | November 30 | 262 days |
| Eureka Wfo Woodley Island, CA | USW00024213 | February 22 | December 7 | 293 days |
| Grizzly Creek SP, CA | USC00043647 | March 4 | November 22 | 264 days |
| Orick Prairie Creek Park, CA | USC00046498 | April 12 | November 6 | 209 days |
| Orleans, CA | USC00046508 | March 12 | November 26 | 262 days |
| Richardson Gr SP, CA | USC00047404 | March 10 | December 1 | 271 days |
| Scotia, CA | USC00048045 | February 1 | December 19 | 328 days |
| Shelter Cove Aviation, CA | USC00048163 | no freeze recorded | no freeze recorded | 365 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
Humboldt County sits in California. That page carries the whole state's zone spread, its metro areas, and every other county in it with a page here.
More of California
- Mendocino County, CA 9a–10a
- Siskiyou County, CA 6b, 7b, 8a, 8b
- Calaveras County, CA 8b–9b
- Lassen County, CA 6a–7a
- Plumas County, CA 6b–8a
- Lake County, CA 8b–9b
- Tehama County, CA 7a, 7b, 9a, 9b
- Tuolumne County, CA 6a, 6b, 7b, 8a, 8b, 9a, 9b
- Trinity County, CA 7b, 8b, 9a
- Modoc County, CA 6b–7a
- Inyo County, CA 7a, 8a, 8b, 9a
- Mariposa County, CA 7a, 8a, 8b, 9a, 9b
Counties with the same zones — 9a–9b
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.
- Soaker hose and drip kitsThe stations here publish no ordinary freeze window, so frost is not what limits the season — water is, through a summer that does not stop.
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.