Extreme Heat Watch for San Diego County until Fri Oct 9, 8pm (National Weather Service). This is the week the bill jumps.
SDG&E time-of-use today: on-peak 4-9pm (most expensive), super off-peak midnight-6am and 10am-2pm (cheapest), off-peak the rest. On TOU-DR1 that's 69.1¢ vs 37.4¢ a kWh (summer rates).
What an hour of AC costs (TOU-DR1)
| Unit | On-peak 4-9pm | Off-peak | Super off-peak |
|---|---|---|---|
| Window unit, 8,000 BTU about 0.8 kW running | $0.55 | $0.37 | $0.30 |
| Window unit, 12,000 BTU about 1.2 kW running | $0.83 | $0.56 | $0.45 |
| Mini-split, 12,000 BTU about 0.6 kW running | $0.41 | $0.28 | $0.22 |
| Central AC, 3 ton about 2.6 kW running | $1.80 | $1.21 | $0.97 |
| Central AC, 4 ton about 3.4 kW running | $2.35 | $1.58 | $1.27 |
| Central AC, 5 ton about 4.3 kW running | $2.97 | $2.00 | $1.61 |
An hour of the compressor running. kW is an estimate (BTU per hour divided by efficiency: window units ~10, mini-splits ~20, central ~14); your unit's nameplate or a plug-in meter gives the real number. Above 130% of baseline on TOU-DR1, the usual case in a heat wave.
Your AC, your day
Hours the compressor actually runs, not hours the thermostat is on.
Cheaper ways through the heat
- Pre-cool: run the AC hard before 4pm, close blinds on the sunny side, then let the house coast and set the thermostat a few degrees higher 4 to 9pm.
- Fans are cheap: a ceiling or box fan draws well under 100 watts, a few cents an hour even on-peak.
- The grid side: SDG&E power today: the windows, the grid this week, what solar exports earn.
- Bill shock: why the bill jumps, where the Climate Credit went and which plan fits.
- No AC, or the power's out: Cool Zones near you · ice delivery.
SDG&E non-CCA total rates, summer season, effective Aug 1, 2026 (SDG&E pricing plans). San Diego Community Power and Clean Energy Alliance customers pay a different generation rate.
Need a human?
This page is built every morning from public data by SideGuy, run by PJ, a local in Solana Beach. If something looks off, or you want a hand with your plans, text PJ at 858-461-8054. A real person answers.
Local help, free to read: make your fix plan · senior benefits checkup · lower your SDG&E bill · Medicare Extra Help · the next 90 days. Plans start as low as $25.
Questions people ask
How much does it cost to run AC in San Diego?
A 3-ton central AC (about 2.6 kW running) costs about $1.80 an hour on SDG&E TOU-DR1 on-peak (4-9pm) and about $0.97 in super off-peak, at summer rates effective Aug 1, 2026.
When is electricity cheapest in San Diego?
On SDG&E time-of-use plans, super off-peak: midnight-6am and 10am-2pm. On-peak is 4-9pm every day.
Does pre-cooling save money?
Yes on time-of-use: moving two hours of a 3-ton AC from on-peak to the 10am-2pm window saves about $1.65 a day on TOU-DR1.
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