Palo Alto saw heat events in March, August, September and October 2026. The City warned of highs of 88 to 91°F during a record-early March heat wave, the National Weather Service issued a Santa Clara Valley heat advisory in August, Bay Area cities set records on September 9, and an October 2 to 8 advisory brought highs up to the low 100s. Palo Alto’s five libraries serve as cooling centers, and ComfortFlow HVAC Palo Alto answers calls 24/7.
2026: the year heat stopped following the calendar
Palo Alto’s climate is mild on paper. The average July high is about 79°F, and many homes were built before central air existed. That is why heat waves here cause so much trouble: homes are not designed for them, and air conditioners that sit idle for months fail the first time they run all day.
In 2026, heat arrived early and stayed late.
| Date | What happened | Source |
|---|---|---|
| March 16 to 20 | Bay Area heat advisory issued unusually early; City of Palo Alto forecast highs of 88 to 91°F | City of Palo Alto; ABC7 |
| August 8 to 9 | NWS heat advisory for the Santa Clara Valley; highs in the mid-90s to low 100s | City of Palo Alto |
| September 9 | Daily records: San Rafael 104°F, Oakland 97°F, SFO 94°F, Half Moon Bay 83°F | KQED |
| October 2 to 8 | NWS heat advisory; weekend highs in the upper 80s to low 100s | City of Palo Alto |
Why so many homes were caught off guard
Most heat-wave service calls we see are not mysterious failures. They are small problems that a long, hot day exposes: - Capacitors and contactors on the outdoor unit that weakened over the summer and fail under load - Dirty filters that restrict airflow until the indoor coil freezes - Clogged condensate drains that trip a safety switch and shut the system off - Undersized or aging systems that run nonstop without reaching the setpoint, especially upstairs - No cooling at all in older homes and Eichlers that were built without central air
When everyone’s system is stressed on the same afternoon, every HVAC company in the area gets busy at once. Preparing in spring is the only way to avoid waiting in line.
Where to cool off in Palo Alto
During heat advisories, the City designates its public libraries as cooling centers during normal hours. In March 2026 the Palo Alto Art Center Auditorium was also listed.
| Cooling center | Address |
|---|---|
| Children’s Library | 1278 Harriet St, 94301 |
| College Terrace Library | 2300 Wellesley St, 94306 |
| Downtown Library | 270 Forest Ave, 94301 |
| Mitchell Park Library | 3700 Middlefield Rd, 94303 |
| Rinconada Library | 1213 Newell Rd, 94303 |
Santa Clara County also publishes a list of cooling centers. People with limited access to cooling, older adults and young children are at highest risk, so check on neighbors.
If your AC fails during a heat wave
- Move anyone vulnerable to the coolest room, or to a library cooling center
- Check the thermostat mode and batteries, the breakers and the furnace power switch
- Replace a dirty filter
- If you see ice on the indoor coil or refrigerant line, turn cooling off and run the fan until it thaws
- Call ComfortFlow HVAC Palo Alto at 650-460-3483, open 24 hours, 7 days a week
More detail in AC not cooling? What to check first.
How to be ready for next year
- Spring tune-up. A maintenance visit in March or April tests capacitors, cleans drains and checks refrigerant before the first heat wave.
- Filters on a schedule. Monthly during hot spells.
- Shade and seal. Close blinds on west-facing windows and seal attic air leaks; it reduces the load on any system.
- Plan the upgrade before it fails. If your AC is over 15 years old, a heat pump replaces both AC and gas furnace, and CPAU pays a $2,500 rebate ($5,000 income-eligible) when it replaces gas heat.
- No central air? Ductless mini-splits add cooling to Eichlers and older homes without new ducts.
Stay current with our Palo Alto HVAC news.