Heat waves and air conditioning costs
In our scenario a central air conditioner running 8 hours a day for 120 days uses 2,082 kWh. At the 2025 U.S. average price of 17.30 cents per kWh that is $360 for the summer. A window unit on the ENERGY STAR list uses 532 kWh a year, about $92.
How the cost is built
The arithmetic is the same everywhere: kWh times price. Central cooling at the median running power of 3-ton class systems on the ENERGY STAR list is 2,169 W. Eight hours a day for 120 days gives 2,082 kWh. That is the same scenario our appliance pages use. It is not a measurement of your house: the right numbers are your own hours and your own bill.
The window-unit figure is different. ENERGY STAR lists an annual kWh for room air conditioners, and the median of 523 models is 532 kWh a year, at a median running power of 709 W. For other appliances see what appliances cost to run.
Heat and price by state
NOAA measures heat load with cooling degree days: how far each day’s average temperature is above 65°F, added up. Among the 48 states with data, the median state has 778 normal cooling degree days. The hottest by this measure are Florida, Arizona, Texas.
In 2025 every one of the 48 states ran above its 1991-2020 normal. Among states with at least the median normal, New Mexico was furthest above, with 1,145 against a normal of 833. Kansas was the closest to normal, with 1,492 against 1,431.
United States, Central air conditioning, our scenario cost per summer, hottest twelve states: EIA retail sales.
CSV| State | Cooling degree days, 1991-2020 normal | Cooling degree days, 2025 | Home price 2025, cents per kWh | Central AC, our scenario, per summer | Window AC, listing figure, per year |
|---|---|---|---|---|---|
| Florida | 3,191 | 3,893 | 15.24 | $317 | $81 |
| Arizona | 2,707 | 3,313 | 15.32 | $319 | $82 |
| Texas | 2,648 | 3,214 | 15.47 | $322 | $82 |
| Louisiana | 2,557 | 3,003 | 12.57 | $262 | $67 |
| Mississippi | 2,126 | 2,525 | 14.03 | $292 | $75 |
| Oklahoma | 1,922 | 2,020 | 13.12 | $273 | $70 |
| Nevada | 1,915 | 2,338 | 13.15 | $274 | $70 |
| Alabama | 1,898 | 2,092 | 16.10 | $335 | $86 |
| South Carolina | 1,838 | 1,972 | 14.96 | $311 | $80 |
| Arkansas | 1,726 | 1,989 | 12.84 | $267 | $68 |
| Georgia | 1,673 | 1,839 | 14.73 | $307 | $78 |
| Kansas | 1,431 | 1,492 | 14.56 | $303 | $77 |
Source: NOAA NCEI nClimDiv statewide cooling degree days (base 65°F, files dated 2026-09-04); EIA retail sales 2025; ENERGY STAR product lists via data/appliances_es.json (2 Oct 2026). Central AC = 2,082 kWh (our scenario of 8 hours a day for 120 days at the median running power of 3-ton class systems); window AC = 532 kWh a year, the median annual figure on the ENERGY STAR room air conditioner list. The twelve states with the most cooling degree days. Retrieved 2026-10-02. CSV, 48 rows.
If cooling kWh moved in step with cooling degree days (our simple assumption, not a measured link), a 2025 summer in New Mexico would have cost about $118 more than a normal one under the scenario. The CSV gives this for every state.
What summer does to a bill
The U.S. average home used 1,166 kWh in July 2025 and 678 in April, 72% more. In New Jersey the gap was 137%. The table shows the eight largest. Part of the gap may not be air conditioning, because we cannot split the load by appliance: no data.
| State | July, kWh per home | April, kWh per home | July above April |
|---|---|---|---|
| New Jersey | 1,133 | 477 | 137% |
| Nevada | 1,425 | 635 | 124% |
| Arizona | 1,662 | 756 | 120% |
| Oklahoma | 1,525 | 726 | 110% |
| Kansas | 1,303 | 621 | 110% |
| Illinois | 1,072 | 526 | 104% |
| South Carolina | 1,510 | 784 | 93% |
| Missouri | 1,452 | 759 | 91% |
Source: EIA monthly retail sales 2025: average kWh per home customer in the month. The eight largest July-over-April gaps. Retrieved 2026-10-02. CSV, 51 rows.
Our seasonal bills guide shows the dollar swing for every state. The time-of-use guide and demand response guide cover plans that reward using less at the hot late-afternoon peak.
Heat risk in the federal data
FEMA’s National Risk Index (December 2025) rates each county for heat wave risk. Of 3,144 counties in the file, 109 are rated Relatively High or Very High (11 Very High), and 121,870,608 people live in them. It is a federal risk rating, not a forecast of the next heat wave.
| State | Counties | Very High or Relatively High heat wave rating | People in those counties |
|---|---|---|---|
| California | 58 | 17 | 29,653,601 |
| Texas | 254 | 13 | 18,298,783 |
| Arizona | 15 | 7 | 6,474,580 |
| Louisiana | 64 | 6 | 1,807,237 |
| Florida | 67 | 5 | 8,581,926 |
| Missouri | 115 | 5 | 2,573,338 |
| New Jersey | 21 | 5 | 3,708,968 |
| New York | 62 | 5 | 8,800,609 |
| Maryland | 24 | 4 | 3,467,196 |
| Illinois | 102 | 3 | 5,795,702 |
Source: FEMA National Risk Index, December 2025 release, county heat wave risk rating (HWAV_RISKR), counted by state; population from the same file. The ten states with the most counties in the two highest classes. Retrieved 2026-10-02. CSV, 51 rows.
NOAA’s Storm Events database also logs heat events. The chart counts them by year.
NOAA heat event reports by year, 2015 to 2025, 2015 to 2025: 11 rows
| Year | Heat reports |
|---|---|
| 2015 | 691 |
| 2016 | 1353 |
| 2017 | 742 |
| 2018 | 2078 |
| 2019 | 2458 |
| 2020 | 2106 |
| 2021 | 2167 |
| 2022 | 3605 |
| 2023 | 8229 |
| 2024 | 5879 |
| 2025 | 4342 |
11 rows from EIA retail sales.
CSVTexas has the most heat event reports in the file for 2015 to 2025 (5,812), then Oklahoma (3,805). These are National Weather Service event reports. They depend on how each forecast office logs events, so compare states with care.
If the bill is too high
37 of the 51 entries in our shutoff tracker have a hot-weather statement in the rule text we read. See shutoff rules by state. The federal LIHEAP program can pay for cooling in some states: in the fiscal 2024 state snapshots, 23 states reported 751,119 households helped with cooling, per the HHS LIHEAP Clearinghouse. Find yours on the state help pages, or start with Arizona help page, Texas help page or Florida help page.
For safety in a heat wave, Ready.gov says to go to a community location with power if heat or cold is extreme, and to check with local officials about heating and cooling locations. If your power fails, see what to do in a power outage and generator safety.
What this page cannot tell you
We do not know your equipment, your hours or your thermostat. The central AC figure is a scenario and the NOAA link between cooling degree days and kWh is an assumption we label. EIA gives state average prices, not your plan: a time-of-use or tiered rate can change the result. We have no data on how many homes have air conditioning in each state.
Key facts and where they come from
| Fact | Value | Source | Date |
|---|---|---|---|
| Central AC, median running power, 3-ton class | 2,169 W | ENERGY STAR heat pump list, via data/appliances_es.json | 2 Oct 2026 |
| Central AC scenario, 8 hours a day for 120 days | 2,082 kWh | Our scenario on the ENERGY STAR list | 2 Oct 2026 |
| Window AC, median annual energy | 532 kWh a year (523 models) | ENERGY STAR room air conditioner list, via data/appliances_es.json | 2 Oct 2026 |
| Window AC, median running power | 709 W | ENERGY STAR room air conditioner list | 2 Oct 2026 |
| U.S. average home price | 17.30 cents per kWh | EIA retail sales, 2025 | 2025 annual |
| Central AC scenario cost at the U.S. price | $360 | Computed | 2025 price |
| States above their normal cooling degree days in 2025 | 48 of 48 | NOAA NCEI nClimDiv | files dated 2026-09-04 |
| Median state normal cooling degree days | 778 | NOAA NCEI nClimDiv, 1991-2020 normals | files dated 2026-09-04 |
| U.S. home use, July vs April 2025 | 1,166 vs 678 kWh | EIA monthly retail sales | 2025 |
| Counties rated Very High or Relatively High for heat wave risk | 109 of 3,144 | FEMA National Risk Index, HWAV_RISKR | December 2025 |
| People in those counties | 121,870,608 | FEMA National Risk Index | December 2025 |
| Heat event reports, 2025 | 4,342 | NOAA NCEI Storm Events, via data/storm_county.json | 2025 |
| States reporting households helped with cooling by LIHEAP | 23 states, 751,119 households | HHS ACF LIHEAP Clearinghouse state snapshots, via data/help_state.json | FY2024 |
Related guides
Questions
How much does it cost to run central air for a summer?
In our scenario, $360 at the U.S. average price, from 2,082 kWh (8 hours a day for 120 days at 2,169 W). Your cost depends on your hours and price.
How much does a window air conditioner use?
The median of 523 ENERGY STAR models uses 532 kWh a year, about $92 at the U.S. average price.
Which states have the most cooling degree days?
By the 1991-2020 normals: Florida, Arizona, Texas. NOAA data covers 48 states; Hawaii and DC have no data.
Was summer 2025 hotter than normal?
By cooling degree days, 48 of 48 states were above their normal in 2025.
How much more power do homes use in July?
U.S. homes used 72% more in July 2025 than in April (1,166 against 678 kWh).
Where is heat wave risk rated highest?
FEMA rates 109 of 3,144 counties Relatively High or Very High. California has the most such counties.
Can my power be shut off in a heat wave?
Some states limit it. 37 of the 51 entries in our tracker carry a hot-weather statement in the rule text. Check your state's row.
Is there help paying a cooling bill?
LIHEAP can help in some states: 23 states reported 751,119 households helped with cooling in fiscal 2024, per the HHS clearinghouse. Check your state page.