United States weather by month

In New York City, the average share of the sky covered by clouds shows mild seasonal variation over the course of the year.

The clearer part of the year begins around June 25 and lasts for 5.2 months, ending around November 28. The clearest month is October, when the sky is clear, mostly clear, or partly cloudy 53% of the time on average.

The cloudier part of the year begins around January 11 and lasts for 5.4 months, ending around June 24. The cloudiest month is April, when it is overcast or mostly cloudy 58% of the time.

This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.

Across the year, average wind speed in New York City is typically calm, near 7 mph, and varies little with the seasons.

The windier part of the year lasts 6.9 months, from around Oct 11 to May 9. The windiest month is March, averaging about 8 mph (light breeze).

The calmer part of the year runs from around May 10 to Oct 10, with August the calmest month at about 6 mph.

Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.

New York City receives about 4.0 kWh/m² a day of solar energy on average — moderate — with a clear seasonal swing between 1.7 and 6.1 kWh/m².

The brighter stretch of the year lasts 6.3 months, from around Mar 14 to Sep 20. The brightest month is July, averaging about 5.9 kWh/m² (bright).

The dimmest month is December, down near 1.8 kWh/m² — roughly 70% less than the July peak.