Pool swim season in Nampa, ID
Swim season in Nampa without a heater, and with one
An unheated pool in Nampa reaches 78°F in Aug, about 1 month a year. The air allows up to 5 swimmable months with a heater (May to Sep).
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What each heater buys you in Nampa
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 1 | Aug | $0 | $0 |
| Solar cover only | 2 | Jul to Aug | $0 | $50 |
| Solar panels + cover | 4 | Jun to Sep | $0 | $283 |
| Heat pump + cover | 5 | May to Sep | $200 | $750 |
| Gas heater + cover | 5 | May to Sep | $226 | $651 |
For a 450 sq ft pool held at 80°F, at ID prices of 13.0¢/kWh electricity and $8/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Nampa
Solar panels + cover: 4 of 5 possible months for about $283 a year all-in, which works out near $94 for each month it adds.
Before you pay for any heater, buy a solar cover: on its own it adds 1 month here for about $50 a year (why a cover comes first). If you get quotes, ask for gas as well as a heat pump: once the purchase price is counted, gas comes out cheaper all-in here (heat pump or gas).
Weather station: Nampa Sugar Factory, 1.3 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Nampa month by month: air, sun and pool water
| Month | Air high | Air avg | Sun kWh/m²/day | Water, unheated | Water, covered | Heat pump $ | Gas $ |
|---|---|---|---|---|---|---|---|
| Jan | 40° | 31° | 1.7 | 30° | 36° | – | – |
| Feb | 47° | 37° | 2.7 | 34° | 40° | – | – |
| Mar | 57° | 45° | 4.0 | 42° | 48° | – | – |
| Apr | 65° | 50° | 5.5 | 50° | 56° | – | – |
| May | 74° | 59° | 6.7 | 58° | 64° | $128 | $140 |
| Jun | 83° | 67° | 7.5 | 67° | 73° | $48 | $58 |
| Jul | 93° | 75° | 7.7 | 76° | 82° | – | – |
| Aug | 92° | 74° | 6.7 | 78° | 84° | – | – |
| Sep | 81° | 64° | 5.2 | 71° | 77° | $24 | $28 |
| Oct | 67° | 52° | 3.5 | 58° | 64° | – | – |
| Nov | 51° | 40° | 2.1 | 45° | 51° | – | – |
| Dec | 40° | 31° | 1.4 | 34° | 40° | – | – |
Heating costs most in May (about $128 with a heat pump, $140 with gas). Sunshine peaks in Jul at 7.7 kWh/m²/day (NASA satellite data, 10.9 km grid cell). Highlighted months are swimmable with no heater.
How Nampa compares with nearby cities
Nampa ranks 6 of 26 Idaho cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Caldwell, ID | 6 mi | 1 | 5 | $200 |
| Meridian, ID | 8 mi | 1 | 5 | $167 |
| Star, ID | 9 mi | 1 | 5 | $200 |
| Middleton, ID | 9 mi | 1 | 5 | $200 |
| Kuna, ID | 9 mi | 1 | 5 | $167 |
| Eagle, ID | 11 mi | 1 | 5 | $200 |