Climate and comfort · independent publisher, not a contractor
Coastal Los Angeles vs the San Fernando Valley
Often yes. On NOAA's 1991–2020 normals, Woodland Hills averages 115.3 days a year at 90 °F or above and LAX 4.8. A Valley house usually needs more capacity and better attic ducts; a coastal house is often better served by a smaller system or a mini-split for a few rooms.
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- The numbers: days at 90 °F and above
- Days at 100 °F and above
- Cooling degree days: how much cooling a season needs
- Station by station
- What each needs
- Does location change the size?
- What it means for cost
- Which system type fits where
- The attic problem in the Valley
- Microclimates in between
- How to read these numbers
- Different code tests, too
The numbers: days at 90 °F and above
The same county, twenty-four times the hot days. Woodland Hills sees about 115 days a year at 90 °F or above; LAX sees about 5. Burbank, at 53.9, sits between them.
Days at 100 °F and above
Why the 100 °F days matter most
Equipment is sized for the hot end of the range, not the average day. Woodland Hills averages 35.6 days a year at 100 °F or above; LAX 0.2. That gap is the main reason a Valley system often needs more capacity.
Cooling degree days: how much cooling a season needs
Cooling degree days add up how far, and for how long, the temperature sits above 65 °F. They track the season's total cooling load, which drives running cost. Woodland Hills totals 1,819; LAX 720.
Station by station
| Station | Days ≥ 90 °F | Days ≥ 100 °F | Cooling degree days |
|---|---|---|---|
| LAX | 4.8 | 0.2 | 720 |
| Long Beach airport | 23.3 | 1.9 | 1,166 |
| Downtown LA (USC) | 25.6 | 1.8 | 1,296 |
| Burbank airport | 53.9 | 7.2 | 1,481 |
| Woodland Hills | 115.3 | 35.6 | 1,819 |
NOAA NCEI, U.S. Climate Normals 1991–2020, annual/seasonal (stations USW00023174, USW00093134, USW00023152, USC00049785).
What each needs
Valley (Woodland Hills, Burbank)
- Capacity that holds the setpoint through the 100 °F days.
- Sealed, insulated attic ducts: attic air on those days is far hotter than outside.
- Shade and clearance around the outdoor unit.
- A serious look at a heat pump, which can also replace the furnace.
Coast (LAX, Santa Monica, Long Beach)
- Often less capacity, sized by load calculation, not floor area.
- Ask about corrosion-resistant coils or coatings near salt air.
- Many homes cool only a few rooms, which favours a mini-split.
- Oversizing is the common mistake: the unit short-cycles and removes less moisture.
Does location change the size?
It changes the load, and the load sets the size. The LA price guides pair about 600 square feet with each ton as a starting point; our estimator shifts that by half a ton for coast or Valley, which is our own rule of thumb and is labelled as such.
Ask for the load calculation
Neither rule of thumb replaces a Manual J load calculation, which accounts for insulation, windows, sun and air leakage on your actual house. Two quotes that differ by a ton should each explain how they sized it.
What it means for cost
A bigger system costs more. Published Los Angeles central AC ranges by size:
For a coastal house that needs cooling in only two rooms, a two-zone mini-split is published at $9,000–$12,500. Full detail is on the cost guide.
Which system type fits where
| House | Often a good fit | Why |
|---|---|---|
| Valley, ducted, gas furnace near the end of its life | Ducted heat pump | Cools through the 100 °F days and replaces the furnace; LADWP or BWP may rebate it |
| Valley, ducted, furnace in good shape | Central AC on sealed ducts | Keeps the furnace; the duct sealing is where the comfort is |
| Coast, ducted, few hot days | A smaller central system or heat pump, sized by load | Oversizing is the common mistake |
| Coast, no ducts, two or three hot rooms | Multi-zone mini-split | Cools only the rooms that need it |
| Anywhere, an ADU or addition | Single-zone mini-split | No duct extension needed |
Our reading of the trade-offs, not a substitute for a load calculation on your house.
The attic problem in the Valley
Most LA ducts run through the attic. On a Valley afternoon the attic is the hottest space on the property, so cooled air loses heat before it reaches the rooms. That is why sealing and insulating ducts matters more in the Valley than at the coast.
ENERGY STAR
"Sealing and insulating ducts can improve the efficiency of your heating and cooling system by as much as 20 percent." On a Valley house with long attic runs, that is often the cheapest comfort gain available.
Microclimates in between
The stations here are points, not borders. Hillside homes, canyon floors and houses a mile or two inland from the beach can sit closer to the next station's numbers. Downtown (USC) at 25.6 days and Long Beach airport at 23.3 are the nearest middle ground.
Use the nearest station as a guide, and let the load calculation on your house settle it.
How to read these numbers
NOAA's climate normals are 30-year averages, here for 1991–2020. A normal of 115.3 days means a typical year, not a guarantee: individual summers run hotter or cooler.
Cooling degree days measure how much and how long it stays above 65 °F, which tracks total cooling need over a season. Days at 100 °F track the peak the equipment must handle.
Different code tests, too
Los Angeles County spans building climate zones 6, 8, 9, 14 and 16. The coast (Santa Monica, Long Beach) is zone 6 and the San Fernando Valley zone 9, so the same change-out can carry different tests a few miles apart. Look up an address with the CEC climate zone tool.
Ask the installer which zone the permit uses. See what Title 24 means for an AC job.
Sources
- NOAA NCEI, U.S. Climate Normals 1991–2020, annual/seasonal (stations USW00023174, USW00093134, USW00023152, USC00049785) (retrieved 2026-09-29)
- California Energy Commission building climate zones (CA State Geoportal); zone assignment by address (retrieved 2026-09-29) — verify before relying on it
- Reliable Heating and Air (Woodland Hills), AC installation cost in LA and Ventura County (retrieved 2026-09-29)
- Cold Cloud (Glendale), central air cost in Los Angeles (retrieved 2026-09-29)
- E & A Mechanical (Tujunga), heat pump installation cost in Los Angeles (retrieved 2026-09-29)
- HVACProjectCost.com, Los Angeles HVAC replacement cost (retrieved 2026-09-29)
Questions
Do I need AC near the beach in LA?
Many coastal homes manage with few hot days (LAX averages 4.8 a year at 90 °F or above). Heat waves still reach the coast, and some homeowners cool one or two rooms rather than the whole house.
Is Burbank closer to the Valley or the coast?
The Valley. Burbank airport averages 53.9 days a year at 90 °F or above on NOAA normals, against 4.8 at LAX.
How much hotter is the Valley than the coast?
On NOAA's 30-year normals, Woodland Hills averages 115.3 days a year at 90 °F or above and 35.6 at 100 °F or above; LAX averages 4.8 and 0.2.
Should a Valley house get a bigger AC?
Often a larger load, so often more capacity, but only a load calculation on your house says how much. Ducts and insulation can change the answer as much as location.
Is a heat pump worth it in the Valley?
It is worth pricing. A heat pump cools like an AC and can replace the furnace. LADWP and Burbank rebate qualifying heat pumps.
What about downtown Los Angeles?
Downtown (USC) averages 25.6 days a year at 90 °F or above, close to Long Beach airport at 23.3.
Does salt air damage outdoor units?
It can speed corrosion near the ocean. Ask the installer about coil coatings or models built for coastal installs, and how the warranty treats coastal locations.
Why does the coast stay so much cooler?
The ocean and the marine layer moderate coastal temperatures. Inland valleys are cut off from that cooling by hills, so they heat up far more on summer afternoons.
Do coastal homes need AC at all?
Many manage with fans and shade most of the year, but heat waves still reach the coast. Some owners cool only bedrooms with a mini-split.
Is a two-stage system worth it in the Valley?
It can be. Two-stage or variable-speed equipment runs longer at low output, which can even out temperatures and humidity. Price both and ask the installer how it suits your load.
Next step
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