Title 24 Reports in Humboldt County

The bay, and every city on it, is zone 1

Humboldt has seven incorporated cities on the California Department of Finance's 2026 estimates — Eureka, Arcata, Fortuna, Ferndale, Rio Dell, Blue Lake and Trinidad — and every ZIP code serving them is zone 1. The populated coast around them is zone 1 as well: McKinleyville, Loleta, Scotia, Orick. In all, 23 of the 35 ZIP codes we derive for the county carry the coastal assignment.

Inside those seven cities a project is permitted by the city; outside them, on unincorporated land, by the county. No zone 2 address in Humboldt lies inside a city, so a zone 2 project here is never a city permit.

Zone 2 is the river country

The other twelve ZIP codes are zone 2, and they belong to the interior valleys. Hoopa and Willow Creek sit on the Trinity River in the north-east; Garberville and Redway sit on the South Fork of the Eel in the south; Alderpoint lies east of them on the main Eel. These are places where summer brings real heat, which the bay rarely has to plan for.

On the Avenue of the Giants the line folds back

South of Scotia the two zones stop behaving like tidy halves. Along the old highway through the redwoods, Redcrest is zone 2; Weott and Miranda, further south, are zone 1; Phillipsville, at the southern end, is zone 2 again, and so are Redway and Garberville beyond it.

Redcrest lies further west than Miranda, yet Redcrest is the inland zone. Distance from the sea does not predict the answer on this stretch. Communities a few minutes apart on one road are assessed against different targets, and only the ZIP code says which.

What changes between Eureka and Garberville

A zone 1 calculation is dominated by keeping heat in through a long, cool, damp year. Zone 2 adds a genuine summer, so shading, glazing orientation and cooling equipment begin to count alongside the heating side. A house designed around Eureka's conditions and built in Garberville is being judged on terms it was not drawn for.

Every ZIP code by zone

Zones per the Energy Commission; county membership and community names per the 2020 Census.

• Climate zone 1 — 95501 (Eureka, Myrtletown); 95503 (Eureka, Bayview, Cutten, Pine Hills, Humboldt Hill, Indianola, Myrtletown); 95519 (McKinleyville, Fieldbrook); 95521 (Arcata, Manila); 95524 (Indianola); 95525 (Blue Lake); 95528; 95536 (Ferndale); 95537 (Fields Landing); 95540 (Fortuna); 95545; 95547 (Hydesville); 95549; 95551 (Loleta); 95553 (Miranda, Myers Flat); 95555 (Orick); 95558; 95562 (Rio Dell); 95564 (Samoa, Fairhaven); 95565 (Scotia); 95570 (Trinidad, Big Lagoon); 95571 (Weott); also 95589, split with a neighbouring county (below)
• Climate zone 2 — 95511 (Alderpoint); 95514; 95542 (Garberville, Benbow); 95546 (Hoopa, Weitchpec); 95550; 95554 (Myers Flat); 95559 (Phillipsville); 95560 (Redway); 95569 (Redcrest); 95573 (Willow Creek); also 95526, 95556, split with a neighbouring county (below)

ZIP codes that cross the county line

• 95589 (Shelter Cove) — about 79% within Humboldt County, the remainder in Mendocino 21%
• 95526 — about 86% within Humboldt County, the remainder in Trinity 14%
• 95556 — about 89% within Humboldt County, the remainder in Siskiyou 11%

The zone for an address in one of these still comes from its ZIP code, which the Energy Commission assigns without regard to the county line. What the split decides is the permitting authority: Humboldt, or Mendocino, Trinity or Siskiyou on the far side. That is worth confirming before a submittal.

Finding the zone for your own project

The zone is set by the project's location and confirmed from the ZIP code against the Energy Commission's published table — not from the county name and not from the nearest large town. Because Humboldt County contains more than one zone, that check decides which set of numbers a report is written against.

Give us the project address and we determine the zone as part of preparing the report. It is the first thing established, because every insulation, glazing and equipment figure downstream depends on it.

Climate zones in Humboldt County

Humboldt County contains California climate zones 1 and 2. The zone drives the insulation, glazing and equipment performance a report has to demonstrate, and it is confirmed from the project ZIP code against the Energy Commission's published table.