Turkey weather by month

In Istanbul, the average share of the sky covered by clouds shows significant seasonal variation over the course of the year.

The clearer part of the year begins around May 1 and lasts for 5.3 months, ending around October 9. The clearest month is July, when the sky is clear, mostly clear, or partly cloudy 94% of the time on average.

The cloudier part of the year begins around October 10 and lasts for 6.7 months, ending around April 30. The cloudiest month is December, when it is overcast or mostly cloudy 66% 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 Istanbul is typically light breeze, near 15 km/h, and varies moderately with the seasons.

The windier part of the year lasts 5.3 months, from around Oct 16 to Mar 26. The windiest month is January, averaging about 17 km/h (light breeze).

The calmer part of the year runs from around Mar 27 to Jul 17, with May the calmest month at about 13 km/h.

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.

Istanbul receives about 4.2 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 1.4 and 7.0 kWh/m².

The brighter stretch of the year lasts 5.9 months, from around Mar 26 to Sep 21. The brightest month is June, averaging about 6.8 kWh/m² (intense).

The dimmest month is December, down near 1.5 kWh/m² — roughly 78% less than the June peak.