The Delta Breeze, SMUD's 5–8 p.m. Peak and Your Thermostat
Updated 2026-10 · Sacramento, CA
How the evening price works
Most SMUD residential customers are on the time-of-day rate. On weekdays the peak runs from 5 to 8 p.m., and from June 1 to September 30 that peak is far more expensive than the rest of the day: SMUD's 2026 rate page lists summer peak electricity at about 37.65 cents a kilowatt-hour against about 15.5 cents off-peak. Weekends and holidays are off-peak all day. The hours when the house is hottest and the family is home are the dearest ones to run the AC.
Pre-cool, then coast
The house itself is a store of coolness. Cool it a few degrees below your usual setting through the afternoon, before 5 p.m., then let the thermostat rise a few degrees through the peak. A well-shaded house with a working system will drift up slowly, and the AC runs less in the expensive window.
- Noon to 5 p.m.: set two to four degrees cooler than usual.
- 5 to 8 p.m.: set two to four degrees warmer than usual, and keep blinds shut.
- After 8 p.m.: back to normal, or off with the windows open once the breeze arrives.
Smart thermostats can do this on a schedule; check that the schedule follows weekdays only, since SMUD's weekends are off-peak.
Let the Delta breeze take the night shift
On most summer evenings, cool marine air pushes inland from the Bay through the Carquinez Strait and into the Valley. Temperatures can fall sharply once it arrives, and it reaches the Pocket, Greenhaven and Land Park first. When the outside air drops below the inside, switch the AC off, open windows on the windward and leeward sides, and run a fan blowing out of the house to pull the cool air through. Close up again in the morning before the outdoor temperature climbs past the indoor. A whole-house fan does the same job faster in houses that have one.
When the breeze fails
Some heat waves come with no breeze at all, and nights that stay in the 70s. Then the pre-cooling still helps, but the system runs most of the night and gets no rest. That is when weak parts fail, and when a system that is short of refrigerant or airflow shows it. If the house is warmer every morning of a heat wave, the system is not keeping up and is worth a look before the next one.
Thermostat settings that cost money
- Fan set to On rather than Auto: the blower runs all day and, with attic ducts, pulls heat back into the house between cycles.
- Large setbacks while you are out on a 105-degree day: the system then runs flat out through the peak to recover.
- A heat pump thermostat using auxiliary electric heat in winter when the heat pump could manage alone.
If the AC cannot hold the pre-cooled temperature at all in the afternoon, or the house gains heat steadily even with the system running, call or send a request and a local heating and air company will check whether the system is working as it should.
Where to go next
Common questions
What are SMUD's peak hours?
On the time-of-day rate, 5 to 8 p.m. on weekdays, with the highest prices from June 1 to September 30. Weekends and holidays are off-peak. Check smud.org for your own rate plan.
Is it cheaper to leave the AC on all day?
On SMUD's time-of-day rate, running it moderately through the afternoon and easing off between 5 and 8 p.m. is usually cheaper than switching it off and recovering during the peak.
What is the Delta breeze?
A sea breeze of cool air that flows from the Bay through the Carquinez Strait into the Sacramento Valley on many warm afternoons and evenings, cooling the city overnight.