Peak sun hours by state
By the editors of SolarPoweredWaterPumps.comLast reviewed October 2026
| State | Annual | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Alabama Huntsville | 4.89 | 3.6 | 4.0 | 4.9 | 5.9 | 6.0 | 6.0 | 5.7 | 5.5 | 5.0 | 4.8 | 4.1 | 3.2 |
| Alaska Anchorage | 3.07 | 0.7 | 1.9 | 3.9 | 5.2 | 5.7 | 5.3 | 4.5 | 3.8 | 2.8 | 1.8 | 0.9 | 0.3 |
| Arizona Phoenix | 6.58 | 5.3 | 6.1 | 7.1 | 7.8 | 7.9 | 7.7 | 6.8 | 6.7 | 6.5 | 6.4 | 5.6 | 4.9 |
| Arkansas Little Rock | 5.10 | 3.8 | 4.3 | 5.1 | 5.8 | 5.9 | 6.4 | 6.0 | 5.9 | 5.3 | 5.0 | 4.2 | 3.5 |
| California Los Angeles | 6.02 | 4.5 | 5.2 | 6.1 | 6.9 | 7.0 | 7.1 | 7.2 | 7.3 | 6.4 | 5.6 | 5.0 | 4.2 |
| Colorado Denver | 5.53 | 4.0 | 4.9 | 5.9 | 6.4 | 6.5 | 7.0 | 6.5 | 6.2 | 5.8 | 5.1 | 4.4 | 3.7 |
| Connecticut Bridgeport | 4.59 | 2.9 | 4.0 | 4.8 | 5.6 | 5.8 | 5.8 | 6.0 | 5.7 | 4.9 | 3.9 | 3.2 | 2.4 |
| Delaware Wilmington | 4.65 | 3.2 | 4.1 | 4.8 | 5.6 | 5.8 | 5.8 | 6.0 | 5.5 | 4.8 | 4.0 | 3.3 | 2.8 |
| District of Columbia Washington | 4.70 | 3.4 | 4.3 | 4.8 | 5.6 | 5.8 | 6.0 | 5.8 | 5.4 | 4.7 | 4.1 | 3.5 | 2.9 |
| Florida Jacksonville | 5.37 | 4.5 | 5.1 | 5.9 | 6.5 | 6.4 | 5.9 | 5.8 | 5.5 | 5.0 | 5.2 | 4.6 | 4.2 |
| Georgia Atlanta | 5.22 | 4.1 | 4.6 | 5.3 | 6.2 | 6.3 | 6.4 | 5.8 | 5.7 | 5.2 | 5.1 | 4.5 | 3.5 |
| Hawaii Honolulu | 5.89 | 5.1 | 5.5 | 5.8 | 6.2 | 6.2 | 6.4 | 6.5 | 6.7 | 6.2 | 5.9 | 5.2 | 5.1 |
| Idaho Boise | 5.15 | 2.6 | 3.7 | 4.9 | 6.3 | 6.9 | 7.3 | 7.4 | 6.9 | 5.9 | 4.6 | 3.0 | 2.3 |
| Illinois Chicago | 4.42 | 2.4 | 3.3 | 4.6 | 5.4 | 5.8 | 6.2 | 6.2 | 5.7 | 4.9 | 3.8 | 2.9 | 1.9 |
| Indiana Indianapolis | 4.53 | 2.8 | 3.7 | 4.6 | 5.4 | 5.8 | 6.1 | 5.9 | 5.7 | 4.9 | 4.1 | 3.2 | 2.2 |
| Iowa Des Moines | 4.69 | 3.1 | 4.1 | 4.8 | 5.4 | 5.8 | 6.0 | 6.3 | 5.8 | 5.0 | 4.2 | 3.4 | 2.5 |
| Kansas Wichita | 5.27 | 4.1 | 4.7 | 5.2 | 5.9 | 6.0 | 6.7 | 6.3 | 6.2 | 5.4 | 5.0 | 4.3 | 3.3 |
| Kentucky Louisville | 4.72 | 3.1 | 3.7 | 4.6 | 5.6 | 5.9 | 6.3 | 5.9 | 5.9 | 5.0 | 4.4 | 3.6 | 2.6 |
| Louisiana New Orleans | 5.23 | 4.3 | 4.7 | 5.7 | 6.1 | 6.2 | 5.8 | 5.3 | 5.3 | 5.3 | 5.5 | 4.8 | 3.8 |
| Maine Portland | 4.36 | 2.9 | 3.8 | 4.7 | 5.4 | 5.5 | 5.4 | 5.8 | 5.5 | 4.8 | 3.5 | 2.8 | 2.2 |
| Maryland Baltimore | 4.67 | 3.3 | 4.2 | 4.9 | 5.6 | 5.8 | 5.9 | 5.9 | 5.4 | 4.7 | 4.1 | 3.4 | 2.7 |
| Massachusetts Boston | 4.54 | 3.1 | 4.0 | 4.8 | 5.5 | 5.6 | 5.6 | 5.9 | 5.7 | 4.9 | 3.8 | 3.1 | 2.5 |
| Michigan Detroit | 4.30 | 2.2 | 3.1 | 4.6 | 5.4 | 5.9 | 6.0 | 6.1 | 5.6 | 4.8 | 3.6 | 2.7 | 1.7 |
| Minnesota Minneapolis | 4.38 | 2.6 | 3.7 | 4.5 | 5.4 | 5.5 | 5.9 | 6.3 | 5.7 | 4.7 | 3.6 | 2.7 | 2.0 |
| Mississippi Jackson | 5.20 | 4.0 | 4.4 | 5.3 | 6.0 | 6.1 | 6.2 | 5.7 | 5.7 | 5.4 | 5.4 | 4.5 | 3.6 |
| Missouri Kansas City | 4.87 | 3.5 | 4.1 | 4.8 | 5.5 | 5.8 | 6.2 | 6.2 | 5.8 | 5.1 | 4.5 | 3.9 | 3.0 |
| Montana Billings | 4.64 | 2.4 | 3.3 | 4.6 | 5.5 | 6.0 | 6.7 | 6.9 | 6.3 | 5.2 | 3.8 | 2.8 | 2.1 |
| Nebraska Omaha | 4.78 | 3.2 | 4.0 | 4.9 | 5.4 | 5.9 | 6.1 | 6.3 | 5.7 | 5.2 | 4.4 | 3.6 | 2.7 |
| Nevada Las Vegas | 6.43 | 4.9 | 5.8 | 6.9 | 7.6 | 7.8 | 7.8 | 6.9 | 7.0 | 6.6 | 6.1 | 5.3 | 4.4 |
| New Hampshire Manchester | 4.38 | 3.0 | 3.8 | 4.7 | 5.4 | 5.4 | 5.3 | 5.7 | 5.5 | 4.8 | 3.6 | 3.0 | 2.3 |
| New Jersey Newark | 4.62 | 3.2 | 4.1 | 4.9 | 5.6 | 5.7 | 5.8 | 5.9 | 5.5 | 4.9 | 4.0 | 3.3 | 2.7 |
| New Mexico Albuquerque | 6.39 | 5.2 | 5.9 | 6.8 | 7.6 | 7.6 | 7.5 | 6.8 | 6.8 | 6.3 | 6.2 | 5.4 | 4.6 |
| New York New York | 4.52 | 3.1 | 4.0 | 4.8 | 5.5 | 5.6 | 5.6 | 5.8 | 5.5 | 4.8 | 3.8 | 3.2 | 2.5 |
| North Carolina Charlotte | 5.10 | 4.0 | 4.7 | 5.4 | 6.0 | 6.1 | 6.2 | 5.7 | 5.5 | 4.9 | 4.8 | 4.3 | 3.5 |
| North Dakota Fargo | 4.22 | 2.2 | 3.1 | 4.0 | 5.5 | 5.6 | 5.9 | 6.4 | 5.7 | 4.6 | 3.4 | 2.4 | 1.8 |
| Ohio Columbus | 4.44 | 2.5 | 3.3 | 4.4 | 5.4 | 5.9 | 6.0 | 5.9 | 5.8 | 4.9 | 3.9 | 3.2 | 2.1 |
| Oklahoma Oklahoma City | 5.47 | 4.5 | 4.9 | 5.4 | 6.1 | 6.0 | 6.7 | 6.5 | 6.3 | 5.6 | 5.2 | 4.7 | 3.7 |
| Oregon Portland | 3.99 | 1.8 | 2.7 | 3.5 | 4.7 | 5.5 | 5.7 | 6.6 | 6.0 | 4.9 | 3.1 | 1.9 | 1.5 |
| Pennsylvania Philadelphia | 4.60 | 3.1 | 4.0 | 4.8 | 5.6 | 5.8 | 5.8 | 5.9 | 5.4 | 4.9 | 3.9 | 3.3 | 2.7 |
| Rhode Island Providence | 4.54 | 3.2 | 4.0 | 4.8 | 5.5 | 5.6 | 5.6 | 5.8 | 5.6 | 5.0 | 3.8 | 3.1 | 2.5 |
| South Carolina Charleston | 5.30 | 4.2 | 4.8 | 5.5 | 6.4 | 6.4 | 6.3 | 6.0 | 5.5 | 5.2 | 5.2 | 4.5 | 3.8 |
| South Dakota Sioux Falls | 4.65 | 2.9 | 3.8 | 4.6 | 5.6 | 5.8 | 6.1 | 6.5 | 5.8 | 5.0 | 4.2 | 3.3 | 2.5 |
| Tennessee Nashville | 4.77 | 3.3 | 3.9 | 4.7 | 5.6 | 5.9 | 6.1 | 5.8 | 5.6 | 5.0 | 4.6 | 3.9 | 2.9 |
| Texas Houston | 5.21 | 4.1 | 4.4 | 5.3 | 5.8 | 6.1 | 6.2 | 5.7 | 5.9 | 5.3 | 5.5 | 4.6 | 3.7 |
| Utah Salt Lake City | 5.26 | 3.2 | 4.1 | 5.3 | 6.1 | 6.6 | 7.3 | 6.9 | 6.5 | 5.8 | 4.9 | 3.6 | 2.7 |
| Vermont Burlington | 4.10 | 2.4 | 3.2 | 4.3 | 5.1 | 5.6 | 5.6 | 5.8 | 5.4 | 4.5 | 3.0 | 2.5 | 1.7 |
| Virginia Virginia Beach | 4.95 | 3.6 | 4.4 | 5.3 | 5.9 | 6.2 | 6.2 | 6.0 | 5.6 | 4.9 | 4.4 | 3.7 | 3.2 |
| Washington Seattle | 3.93 | 1.5 | 2.7 | 3.6 | 5.1 | 5.8 | 5.9 | 6.4 | 5.8 | 4.5 | 2.8 | 1.8 | 1.3 |
| West Virginia Charleston | 4.44 | 2.6 | 3.4 | 4.4 | 5.5 | 5.8 | 6.0 | 5.7 | 5.5 | 4.7 | 3.9 | 3.4 | 2.4 |
| Wisconsin Milwaukee | 4.45 | 2.5 | 3.4 | 4.8 | 5.4 | 5.9 | 6.2 | 6.2 | 5.7 | 4.8 | 3.7 | 2.8 | 2.1 |
| Wyoming Cheyenne | 5.28 | 3.7 | 4.5 | 5.7 | 6.1 | 6.2 | 6.9 | 6.4 | 6.1 | 5.6 | 4.8 | 4.0 | 3.2 |
How these figures are made
The radiation data is NREL's National Solar Radiation Database, read through PVGIS v5.2 from the European Commission's Joint Research Centre (Alaska falls outside the NSRDB grid and is served from ERA5). Each state is modelled at its largest city, on a panel facing due south at 20 degrees of tilt. Annual peak sun hours are the annual irradiation on that plane divided by 365; monthly figures are recovered from PVGIS's monthly output. Full derivation on the methodology page.
A big state is not one climate. El Paso is sunnier than Houston and eastern Washington sunnier than Seattle; if your site is far from the city named, check your exact location in PVWatts (National Laboratory of the Rockies, formerly NREL). Tilting panels steeper than 20 degrees raises winter sun hours and lowers summer ones, which suits a year-round stock well.