Turkey is a large country and much of the north and west coast benefits from quite mild winters and hot summers. Peak season is June, July and August when you can expect great weather across the country, but also crowds at the popular beach areas and the historical sights.
May and September are lovely months to get a good balance, as crows are reduced and the weather is still good. This ‘shoulder season’ is the perfect time to visit Cappadoccia in the centre of the country. April and October are less reliable weather wise country-wide, but even seasonal sights are usually still open and you can benefit from reduced prices, and these are great months for Istanbul and the southern Mediterranean coast in particular.
Ski season kicks in around November to March, but outside of the resorts the country is quiet for tourism and many highlights will be closed.
Best months are noted on each individual itinerary as well, visit the Holidays & Prices page to view these.