Pool swim season in Hawthorne, NJ
When can you swim in an outdoor pool in Hawthorne, NJ?
An unheated pool in Hawthorne never reaches 78°F in a normal year. It peaks around 77°F in Aug. The air allows up to 5 swimmable months with a heater (May to Sep).
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What each heater buys you in Hawthorne
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 0 | no month | $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 | $322 | $872 |
| Gas heater + cover | 5 | May to Sep | $374 | $799 |
For a 450 sq ft pool held at 80°F, at NJ prices of 24.1¢/kWh electricity and $14/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Hawthorne
Solar panels + cover: 4 of 5 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 2 months 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: Little Falls, 6.1 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Hawthorne 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 | 39° | 31° | 1.9 | 32° | 38° | – | – |
| Feb | 41° | 32° | 2.8 | 31° | 37° | – | – |
| Mar | 51° | 41° | 3.7 | 37° | 43° | – | – |
| Apr | 63° | 51° | 4.9 | 48° | 54° | – | – |
| May | 73° | 62° | 5.4 | 59° | 65° | $222 | $250 |
| Jun | 82° | 71° | 6.0 | 69° | 75° | $63 | $80 |
| Jul | 87° | 76° | 6.0 | 76° | 82° | – | – |
| Aug | 84° | 74° | 5.2 | 77° | 83° | – | – |
| Sep | 76° | 66° | 4.3 | 71° | 77° | $37 | $44 |
| Oct | 65° | 55° | 3.0 | 60° | 66° | – | – |
| Nov | 54° | 45° | 2.2 | 49° | 55° | – | – |
| Dec | 44° | 35° | 1.6 | 39° | 45° | – | – |
Heating costs most in May (about $222 with a heat pump, $250 with gas). Sunshine peaks in Jul at 6.0 kWh/m²/day (NASA satellite data, 58.4 km grid cell). Highlighted months are swimmable with no heater.
How Hawthorne compares with nearby cities
Hawthorne ranks 87 of 116 New Jersey cities for unheated swim months; Fair Lawn, Elmwood Park nearby get a longer season without a heater.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Glen Rock, NJ | 2 mi | 0 | 5 | $322 |
| Fair Lawn, NJ | 3 mi | 2 | 5 | $232 |
| Ridgewood, NJ | 3 mi | 0 | 5 | $322 |
| Paterson, NJ | 3 mi | 0 | 5 | $322 |
| Elmwood Park, NJ | 4 mi | 2 | 5 | $232 |
| Franklin Lakes, NJ | 4 mi | 0 | 5 | $387 |