Guernsey · Planning for the seasons
Climate and seasonal solar data
See how regional sunlight, temperature, rain and wind vary through the year. Use this context when comparing homes or preparing questions about solar panels—not to judge a particular roof.
NASA POWER long-term monthly averages, January 2001–December 2020. Imported and checked 21 September 2026. These are not current weather observations or a forecast.
Solar energy through the year
Average daily energy arriving on a horizontal surface, in kWh/m²/day. The table below provides the exact values.
A seasonal pattern for this model point, not a comparison of individual properties. A tilted roof, local shade and system losses change panel output.
Monthly climate data
| Month | Solar energy kWh/m²/day | Mean air temp. °C | Precipitation mm/day | Wind at 10 m m/s |
|---|---|---|---|---|
| JAN | 0.87 | 9.1 | 3.11 | 9.15 |
| FEB | 1.62 | 8.3 | 2.81 | 8.74 |
| MAR | 2.89 | 8.7 | 2.21 | 7.81 |
| APR | 4.66 | 10.0 | 1.57 | 6.35 |
| MAY | 5.68 | 11.9 | 1.64 | 6.04 |
| JUN | 6.04 | 14.2 | 1.55 | 5.45 |
| JUL | 5.88 | 16.1 | 1.50 | 5.49 |
| AUG | 4.90 | 17.0 | 1.74 | 5.85 |
| SEP | 3.73 | 16.5 | 1.56 | 6.60 |
| OCT | 2.09 | 14.9 | 3.09 | 7.83 |
| NOV | 1.09 | 12.4 | 3.65 | 8.75 |
| DEC | 0.70 | 10.2 | 3.43 | 9.16 |
What this helps you ask
Ask a solar installer for monthly generation estimates as well as an annual total. Compare those with when your household uses electricity. Winter demand and summer generation need not match.
For a home survey, ask about insulation, ventilation, drainage and local exposure. Regional rain and wind averages cannot establish the condition of a building.
What the data cannot show
This is a coarse regional model, sampled near St Peter Port, not a weather station on a property. It cannot resolve roof angle, trees, neighbouring buildings, street-level wind, damp, flood risk or future climate.
It is not separate evidence for Alderney, Sark or Herm. No property solar score, energy certificate, savings estimate or installation recommendation is derived from these numbers.
Sources, coverage and reuse
Data provided by the NASA POWER project. View the original NASA POWER response (opens in a new tab). Requested point: 49.455° latitude, -2.536° longitude. Solar radiation and meteorological variables use source grids; the coordinates do not imply property-level resolution.
NASA POWER data documentation (opens in a new tab) · NASA data-use guidance (opens in a new tab). Independent interpretation; no provider endorsement.