Pool swim season in Hillsdale, NJ
When can you swim in an outdoor pool in Hillsdale, NJ?
An unheated pool in Hillsdale reaches 78°F in Jul to Aug, about 2 months a year. The air allows up to 5 swimmable months with a heater (May to Sep).
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Heater options for a Hillsdale pool, side by side
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 2 | Jul to Aug | $0 | $0 |
| Solar cover only | 3 | Jul to Sep | $0 | $50 |
| Solar panels + cover | 4 | Jun to Sep | $0 | $283 |
| Heat pump + cover | 5 | May to Sep | $238 | $788 |
| Gas heater + cover | 5 | May to Sep | $282 | $707 |
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 Hillsdale
Solar panels + cover: 4 of 5 possible months for about $283 a year all-in, which works out near $142 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: Teterboro Airport, 10.3 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Hillsdale 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° | 33° | 1.8 | 34° | 40° | – | – |
| Feb | 43° | 35° | 2.6 | 34° | 40° | – | – |
| Mar | 51° | 42° | 3.6 | 39° | 45° | – | – |
| Apr | 63° | 53° | 4.6 | 49° | 55° | – | – |
| May | 73° | 63° | 5.3 | 60° | 66° | $194 | $224 |
| Jun | 82° | 73° | 5.8 | 71° | 77° | $43 | $56 |
| Jul | 87° | 78° | 5.9 | 78° | 84° | – | – |
| Aug | 85° | 76° | 5.1 | 79° | 85° | – | – |
| Sep | 78° | 69° | 4.2 | 74° | 80° | $1 | $2 |
| Oct | 67° | 57° | 2.8 | 63° | 69° | – | – |
| Nov | 56° | 47° | 2.0 | 51° | 57° | – | – |
| Dec | 45° | 38° | 1.4 | 41° | 47° | – | – |
Heating costs most in May (about $194 with a heat pump, $224 with gas). Sunshine peaks in Jul at 5.9 kWh/m²/day (NASA satellite data, 66.7 km grid cell). Highlighted months are swimmable with no heater.
How Hillsdale compares with nearby cities
Hillsdale ranks 37 of 116 New Jersey cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Westwood, NJ | 1 mi | 2 | 5 | $232 |
| Ridgewood, NJ | 4 mi | 0 | 5 | $322 |
| Waldwick, NJ | 4 mi | 0 | 5 | $387 |
| Paramus, NJ | 4 mi | 2 | 5 | $232 |
| Dumont, NJ | 5 mi | 2 | 5 | $227 |
| New Milford, NJ | 5 mi | 2 | 5 | $232 |