Pool swim season in Greenfield, MA
Greenfield, MA: how long the pool season really is
An unheated pool in Greenfield never reaches 78°F in a normal year. It peaks around 72°F in Aug. The air allows up to 4 swimmable months with a heater (Jun to Sep).
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Heater options for a Greenfield pool, side by side
| 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 | $360 | $910 |
| Gas heater + cover | 4 | Jun to Sep | $603 | $1,028 |
For a 450 sq ft pool held at 80°F, at MA prices of 30.2¢/kWh electricity and $25/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Greenfield
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: Greenfield #3, 3 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Greenfield 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 | 33° | 24° | 1.8 | 26° | 32° | – | – |
| Feb | 37° | 26° | 2.6 | 24° | 30° | – | – |
| Mar | 45° | 34° | 3.7 | 31° | 37° | – | – |
| Apr | 59° | 46° | 4.7 | 42° | 48° | – | – |
| May | 70° | 57° | 5.3 | 54° | 60° | – | – |
| Jun | 78° | 66° | 5.7 | 64° | 70° | $165 | $278 |
| Jul | 83° | 71° | 5.9 | 71° | 77° | $41 | $74 |
| Aug | 81° | 69° | 5.3 | 72° | 78° | $27 | $47 |
| Sep | 74° | 62° | 4.3 | 67° | 73° | $127 | $204 |
| Oct | 62° | 51° | 2.7 | 56° | 62° | – | – |
| Nov | 50° | 39° | 1.9 | 44° | 50° | – | – |
| Dec | 40° | 30° | 1.4 | 33° | 39° | – | – |
Heating costs most in Jun (about $165 with a heat pump, $278 with gas). Sunshine peaks in Jul at 5.9 kWh/m²/day (NASA satellite data, 15.0 km grid cell). Highlighted months are swimmable with no heater.
How Greenfield compares with nearby cities
Greenfield ranks 48 of 58 Massachusetts cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Amherst Town, MA | 18 mi | 0 | 4 | $325 |
| Northampton, MA | 20 mi | 0 | 4 | $325 |
| Easthampton, MA | 24 mi | 0 | 5 | $601 |
| North Adams, MA | 27 mi | 0 | 4 | $472 |
| Keene, NH | 28 mi | 0 | 4 | $458 |
| Holyoke, MA | 28 mi | 0 | 5 | $601 |