Istanbul is blessed with a diverse climatic landscape (such as the blending of land, mountains and seas), that make the weather as diverse as its cultural settings. As a result of this quirky geographic location, the different regions of Istanbul also offer different climatic conditions. The only thing that is safe to say about the weather is that Istanbul is a particularly windy city (with an average wind speed of 17 kilometers per hour). The Asian Side generally has milder conditions, while the European Side is colder.
The city’s interior offers a different climate at the coasts. The coastal areas (Mediterranean and Aegean coasts) are generally moderately dry and hot during summers and cool and rainy during the winters. As one goes into the east, there is less rainfall, with the Black Sea getting most of these blessed drops.
The Anatolian side, particularly the Anatolian Plateau, has extreme winters, with snow for almost a third of the year. Here, temperatures can go down to -40 degrees Celsius. Going east 
into the Anti-Taurus Mountain region, summers are likely to be very dry and hot, while winters are marked with heavy snow and bitter cold. Istanbul, along the Sea of Marmara, has a more moderate climate, but winters can still see temperatures below zero. The Bosphorus Strait area, meanwhile, takes more to the Mediterranean climate (wet winters and dry summers). Swimming in this area is best done starting from the tail end of April down to month of October.
In sum, Istanbul has all four seasons – short and sweet springs, warm and toasty summers, long autumns with winters marked by rain and snow. Come spring, the Bosphorus is clothed in purple splendor as the Judas-trees along it come into full bloom. Tulips and spring flowers also give a lovely color to a Bosphorus spring. June eases from spring into summer (which is, as a rule, hot and humid).
There may be a bit of rainfall, but you can expect that after a few minutes of rain, the sun will be back and smiling again. And the mild weather continues until the end of September. Then comes a long autumn period. Come winter time, expect some snowfall, although in some cases, there may only be cold rain and no snow. However, it won’t come down to freezing point. The best time to come to Istanbul is during autumn and spring, when the weather is mild – neither hot nor cold, just right. As such, these months are where there is the highest concentration of tourists into the city. July is the warmest month, while January is the city’s coldest month.
The general rule when it comes to the weather is to be cautious always, as you may be caught unawares with heavy rains but without an umbrella.
