California Climate Zone 8

Climate zone 8 covers the first band inland from the Southern California coast, behind zone 6 but short of the valleys. The Energy Commission assigns 188 of California's ZIP codes to it, making it the 6th largest of the sixteen.

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Where zone 8 is

The Energy Commission assigns 188 ZIP codes to zone 8 — about 7.0 per cent of every ZIP code it lists, and the 6th largest of the sixteen. Places in it include Anaheim, Santa Ana, Irvine, Inglewood, Compton, Downey and Cerritos.

The zone is geographically contiguous — it occupies one continuous block of the state rather than being scattered. The ZIP codes fall in the prefix ranges 900xx, 901xx, 902xx, 903xx, 905xx, 906xx, 907xx, 908xx, 926xx, 927xx, 928xx.

What drives compliance in zone 8

The first step inland is where cooling becomes a real constraint. Without the coastal moderation of zone 6, summer cooling loads rise noticeably while heating stays light, so equipment efficiency and glazing solar heat gain start to dominate the outcome.

Where zone 8 ends

Zone 8 sits sandwiched between the coastal strip and the inland valleys, which makes it easy to misidentify from an address alone. Irvine and Santa Ana are in it while Newport Beach and Costa Mesa, a few miles seaward, are not — the line runs behind the beach rather than along it.

Boundaries follow conditions rather than administrative lines, so the assignment is resolved from the project ZIP code rather than inferred from the city on the drawings.

Cities we cover in zone 8

5 of our city guides cover places in this zone, and some of them cross a zone boundary inside the city.