North Country · Adirondack Interior
St. Lawrence 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
Adirondack Interior
Specific yield
1,020–1,160 kWh / kW-DC / yr
A 10 kW array averages about 10,900 kWh a year here.
Modeled NREL PVWatts v8 · verified Jan 2026
Mean annual snowfall
90–180 inches
Minor lake-effect exposure.
Modeled NOAA/NWS seasonal snowfall records · verified Jan 2026
Design ground snow load
70–130 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 2026
Winter quarter share
10% of annual
December, January, and February combined.
Derived NREL PVWatts v8 · verified Jan 2026
Days with snow on the array
35–75 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 Adirondack Interior yield band. Bar height is relative to the peak month.
Show the arithmetic
10 kW × 1,090 kWh/kW/yr (midpoint of the Adirondack Interior band) = 10,900 kWh a year, distributed on a northern-temperate seasonal curve anchored so December through February sums to 10% 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
- Tree shading is the dominant production variable. Mature conifers do not drop their needles in winter, so they shade year-round in exactly the season you can least afford it.
- Restoration times after major storms are the longest in the state. Backup power here is a practical utility, not a luxury.
- Clear, cold, high-elevation days produce very well — panels are more efficient cold. The problem is how few of those days there are between November and February.
The roof
Consequences for the array itself
- Site-specific structural review is the norm, not the exception.
- Metal roofs are common and simplify attachment, but standing-seam clamps must match the seam profile.
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 St. Lawrence County is 70–130 psf. At this load, structural review is genuine engineering and some roofs will need reinforcement. That is a finding, not a sales objection.
Microclimates
St. Lawrence County is not one climate
| Zone | Snowfall | Snow load | Specific yield |
|---|---|---|---|
| Adirondack Interior (primary) | 90–180" | 70–130 psf | 1,020–1,160 kWh/kW |
| Lake Ontario Plain | 80–140" | 50–80 psf | 1,080–1,220 kWh/kW |
By location
Elevation across St. Lawrence County
| Place | Elevation | Climate zone | Guide |
|---|---|---|---|
| Potsdam | 450 ft | Adirondack Interior | Costs & production |
| Massena | 210 ft | Adirondack Interior | Costs & production |
Questions
St. Lawrence County climate FAQ
- How much does snow reduce solar production in St. Lawrence County?
- Less than most people expect. A pitched array here sees roughly 35 to 75 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 70 to 130 psf, and racking must be engineered and stamped for it.
- What is the seasonal production curve in St. Lawrence County?
- Jul is the strongest month and Dec the weakest, by roughly 4.4 to one. December through February combined account for about 10% 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 St. Lawrence 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 10,900 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.
- How does lake-effect snow affect solar in St. Lawrence County?
- Minor exposure. Tree shading is the dominant production variable. Mature conifers do not drop their needles in winter, so they shade year-round in exactly the season you can least afford it.
- Does cold weather help or hurt solar panels in St. Lawrence 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.