Pool swim season in Cambridge, MD
Cambridge, MD: how long the pool season really is
An unheated pool in Cambridge 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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What each heater buys you in Cambridge
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 2 | Jul to Aug | $0 | $0 |
| Solar cover only | 4 | Jun to Sep | $0 | $50 |
| Solar panels + cover | 5 | May to Sep | $0 | $283 |
| Heat pump + cover | 5 | May to Sep | $125 | $675 |
| Gas heater + cover | 5 | May to Sep | $193 | $618 |
For a 450 sq ft pool held at 80°F, at MD prices of 21.3¢/kWh electricity and $16/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Cambridge
Solar cover only: 4 of 5 possible months for about $50 a year all-in, which works out near $25 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: Royal Oak 2 SSW, 12.7 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Cambridge 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 | 45° | 37° | 2.2 | 38° | 44° | – | – |
| Feb | 47° | 39° | 3.0 | 38° | 44° | – | – |
| Mar | 56° | 46° | 4.0 | 44° | 50° | – | – |
| Apr | 67° | 57° | 5.1 | 54° | 60° | – | – |
| May | 75° | 66° | 5.8 | 64° | 70° | $121 | $186 |
| Jun | 84° | 75° | 6.4 | 74° | 80° | $4 | $7 |
| Jul | 88° | 79° | 6.3 | 80° | 86° | – | – |
| Aug | 86° | 77° | 5.6 | 81° | 87° | – | – |
| Sep | 80° | 71° | 4.5 | 76° | 82° | – | – |
| Oct | 69° | 60° | 3.4 | 66° | 72° | – | – |
| Nov | 58° | 49° | 2.5 | 54° | 60° | – | – |
| Dec | 49° | 41° | 1.9 | 44° | 50° | – | – |
Heating costs most in May (about $121 with a heat pump, $186 with gas). Sunshine peaks in Jun at 6.4 kWh/m²/day (NASA satellite data, 37.3 km grid cell). Highlighted months are swimmable with no heater.
How Cambridge compares with nearby cities
Cambridge ranks 6 of 23 Maryland cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Easton, MD | 15 mi | 2 | 5 | $125 |
| Salisbury, MD | 29 mi | 2 | 6 | $223 |
| Annapolis, MD | 37 mi | 2 | 5 | $105 |
| Milford, DE | 43 mi | 1 | 5 | $182 |
| Bowie, MD | 45 mi | 1 | 5 | $204 |
| La Plata, MD | 48 mi | 0 | 5 | $220 |