Pool swim season in Manchester, NH
Swim season in Manchester without a heater, and with one
An unheated pool in Manchester never reaches 78°F in a normal year. It peaks around 73°F in Aug. The air allows up to 4 swimmable months with a heater (Jun to Sep).
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What each heater buys you in Manchester
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 0 | no month | $0 | $0 |
| Solar cover only | 1 | Aug | $0 | $50 |
| Solar panels + cover | 4 | Jun to Sep | $0 | $283 |
| Heat pump + cover | 4 | Jun to Sep | $327 | $877 |
| Gas heater + cover | 4 | Jun to Sep | $455 | $880 |
For a 450 sq ft pool held at 80°F, at NH prices of 26.9¢/kWh electricity and $19/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Manchester
Solar panels + cover: 4 of 4 possible months for about $283 a year all-in, which works out near $71 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 a heat pump sized to your pool's surface area; here it beats gas all-in (heat pump or gas).
Weather station: Massabesic Lake, 2.6 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Manchester 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 | 32° | 22° | 1.8 | 25° | 31° | – | – |
| Feb | 35° | 25° | 2.7 | 23° | 29° | – | – |
| Mar | 43° | 33° | 3.7 | 30° | 36° | – | – |
| Apr | 56° | 46° | 4.7 | 41° | 47° | – | – |
| May | 67° | 57° | 5.3 | 53° | 59° | – | – |
| Jun | 76° | 66° | 5.7 | 64° | 70° | $156 | $218 |
| Jul | 81° | 71° | 6.0 | 71° | 77° | $38 | $57 |
| Aug | 80° | 69° | 5.3 | 73° | 79° | $22 | $32 |
| Sep | 73° | 62° | 4.3 | 67° | 73° | $111 | $148 |
| Oct | 60° | 50° | 2.8 | 56° | 62° | – | – |
| Nov | 48° | 39° | 2.0 | 44° | 50° | – | – |
| Dec | 38° | 29° | 1.5 | 33° | 39° | – | – |
Heating costs most in Jun (about $156 with a heat pump, $218 with gas). Sunshine peaks in Jul at 6.0 kWh/m²/day (NASA satellite data, 54.1 km grid cell). Highlighted months are swimmable with no heater.
How Manchester compares with nearby cities
Manchester ranks 3 of 11 New Hampshire cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Nashua, NH | 16 mi | 0 | 4 | $228 |
| Concord, NH | 18 mi | 0 | 4 | $334 |
| Methuen, MA | 21 mi | 0 | 4 | $196 |
| Haverhill, MA | 23 mi | 0 | 4 | $356 |
| Lawrence, MA | 24 mi | 0 | 4 | $196 |
| Lowell, MA | 25 mi | 0 | 5 | $647 |