Do you need air conditioning in San Diego?

The honest answer depends on where you live, how your house holds heat, and how you cope with the hottest stretch of the year. Here is what the public figures say, and how to think it through.

What the weather figures show

NOAA’s 1991 to 2020 normals for San Diego Lindbergh Field, on the bay, give a picture of the coast:

Measure	Normal at Lindbergh Field
Average high, January	66.4 F
Average high, July	75.3 F
Average high, August	77.3 F
Average high, September	77.2 F
Rain in August	0.01 in
Rain in a year	9.79 in
Cooling degree days in a year	893

Those are gentle numbers. The average August high at the coast is under 80 F, and the warmest stretch is short: August and September. Cooling degree days are a measure of how much cooling weather a place gets in a year, and 893 is modest. On averages alone, the coast asks little of an air conditioner.

Averages are not the whole story

Two things change the picture. First, the station is on the coast. Inland neighborhoods and East County often run warmer than the coast, so a house in Mira Mesa, Rancho Bernardo, Tierrasanta, El Cajon or Santee can see a different late summer from one in Pacific Beach or Point Loma. Second, averages hide the extremes. San Diego has had record heat waves, and a few days of unusual heat can make a house without cooling hard to sleep in.

Questions to ask about your own home

• Does the house face the afternoon sun, or have large west-facing windows?
• Is there a room upstairs, over the garage or under the attic that is always the warmest?
• Does anyone in the home work from home through the afternoon?
• How did the house feel in the last heat wave?
• Do you already have ducts from a furnace that a central system or heat pump could use?

If most of the answers point to a warm house, cooling is worth pricing. If one room is the problem, a single ductless head may be all you need.

If you decide yes: the options

Option	When it fits
A ductless mini split for one room or a few	No ducts, or one or two rooms that run hot; see mini split installation
A central AC	The house has ducts in good shape; see AC installation
A heat pump	You want cooling and heating in one system, or the furnace is old too; see heat pump installation

In the City of San Diego, the Development Services Department says air conditioning systems may not be installed without a mechanical permit, and California’s Energy Code applies to new systems. Anyone you hire for the job needs a CSLB license, and the class for this work is C-20. Ask the contractor and SDG&E about current rebates or incentives.

What a contractor will ask

If you ask a contractor about adding cooling, expect questions about the house rather than a quick price: how many rooms you want cooled, whether there are ducts, where an outdoor unit could sit, and whether the electrical panel has room for it. General practice is to size a system with a load calculation for the house itself. Ask how they worked out the size, and get the estimate in writing. The HVAC contractor guide covers how to check a contractor’s license on cslb.ca.gov before you sign.

If you decide no

If you go without AC, plan for the hot spells. During a heat wave, San Diego County lists air-conditioned Cool Zones, such as libraries and community centers, that anyone can use; check the County’s Cool Zones page. If someone shows signs of heat stroke, call 911. The San Diego heat wave guide has more.

Air Conditioning Repair San Diego is an independent referral service, not an air conditioning or HVAC company. Calls and form requests are passed to an independent local AC and HVAC contractor, who can contact you about your system; that contractor gives any quote and does any work.

Questions people ask