Long Island · Long Island
Nassau County weather and solar
What the climate here actually does to a solar array — production by season, the structural spec the snow load forces, and the roof decisions that follow from both.
The climate
Long Island
Specific yield
1,220–1,360 kWh / kW-DC / yr
A 10 kW array averages about 12,900 kWh a year here.
Modeled NREL PVWatts v8 · verified Jan 2026
Mean annual snowfall
20–45 inches
No lake-effect exposure.
Modeled NOAA/NWS seasonal snowfall records · verified Jan 2026
Design ground snow load
20–30 psf
Racking and structural review are engineered to this figure. Ask which number your proposal used.
Filed ASCE 7 ground snow load data · verified Jan 2026Snow load is low here, but wind load requirements are the highest in the state and drive the racking spec instead.
Winter quarter share
14% of annual
December, January, and February combined.
Derived NREL PVWatts v8 · verified Jan 2026
Days with snow on the array
3–12 per season
Far fewer than days with snow on the ground — panels shed.
Observed GridReady quote and bill review sample · verified Jan 2026
Seasonality
Production month by month on a 10 kW array
kWh per month from a 10 kW-DC array at the midpoint of the Long Island yield band. Bar height is relative to the peak month.
Show the arithmetic
10 kW × 1,290 kWh/kW/yr (midpoint of the Long Island band) = 12,900 kWh a year, distributed on a northern-temperate seasonal curve anchored so December through February sums to 14% of the total.
A modeled shape, not a measurement of your roof. Orientation, pitch, and shading move individual months more than they move the annual total.
Derived NREL PVWatts v8 · verified Jan 2026
Local weather
What the weather here specifically does
- Coastal exposure means wind, not snow, sets the structural spec. Attachment density and uplift calculations here are genuinely stricter than upstate.
- Salt air is a real corrosion consideration within a mile or two of the water. Ask what the racking and fastener finish is rated for.
- Hurricane and nor'easter restoration history is the honest basis for a storage decision here — multi-day, island-wide outages are within living memory for most homeowners.
The roof
Consequences for the array itself
- Higher attachment counts than upstate for the same array. That is code, not upselling.
- Stainless or coated hardware near the shoreline is worth paying for.
The one question worth asking every installer here
“What ground snow load is this racking engineered for, and can I see the stamped calculation?” The right answer in Nassau County is 20–30 psf. A proposal that cannot answer has not been engineered for this roof.
By location
Elevation across Nassau County
| Place | Elevation | Climate zone | Guide |
|---|---|---|---|
| Levittown | 60 ft | Long Island | Costs & production |
| Freeport | 20 ft | Long Island | Costs & production |
Questions
Nassau County climate FAQ
- How much does snow reduce solar production in Nassau County?
- Less than most people expect. A pitched array here sees roughly 3 to 12 days a season with enough cover to stop production — the glass is slick and the array runs warmer than the shingles around it. Cloud cover through November and December costs more production than snow cover does. What snow really drives is the structural spec: design ground snow load here is 20 to 30 psf, and racking must be engineered and stamped for it.
- What is the seasonal production curve in Nassau County?
- Jul is the strongest month and Nov the weakest, by roughly 3 to one. December through February combined account for about 14% of annual output — roughly one month's worth of production spread across three months. A proposal that shows a smooth, near-flat monthly production curve for this county is not modeling this climate.
- Is Nassau County too far north or too cloudy for solar?
- No, but the honest framing is that the climate sets the ceiling and the electricity rate sets the value. A 10 kW array here produces roughly 12,900 kWh a year. That is real output — the question is what a kWh is worth where you live, which is a rate question rather than a weather one.
- Does cold weather help or hurt solar panels in Nassau County?
- Cold helps efficiency — panels produce more per unit of sunlight at low temperature, which is why a clear February day can outperform a hazy July one on a per-hour basis. What hurts is daylight hours and cloud cover, and this climate is short on both between November and February. The two effects do not cancel out; the daylight loss dominates.
Next step
Turn this into your own numbers
The climate sets what a roof can produce. Your rate sets what that production is worth, and your roof sets how much of the band you actually get.
How this page is built
This is a generated page: the structure is shared across locations, the numbers are not. Every figure comes from the source cited beside it, with the date we last checked it. Nothing here is a quote, an appraisal, or tax advice, and none of it is specific to your roof.
Rates and incentive programs change. We re-verify utility tariffs and NYSERDA program status on a rolling schedule and stamp the date on each number rather than on the page, so you can see which specific figures are fresh. Full methodology · Program status tracker · About the Local Energy Playbook
Page content last reviewed April 2026.