Best Times to Visit Istanbul
The best time to visit Istanbul is September to November. That's when the crowds diminish, the rates drop, and weather is spectacular. Peak season -- summer -- sees spikes in temperatures and room rates. To save money and sweat less, visit Istanbul in the spring or fall. Spring is still a little chilly, so bring a coat. The winter months tend to be rainy, snowy and cold with average highs in the 40s. The dip in temperatures (and thus tourism) means that you'll find bargains on hotel rates; the budget conscious could brave the weather and visit in December or January.
Visitors will be greeted by comfortable temperatures (60s and 70s in the day) and affordable prices on hotels and airfare. This three-month window is sandwiched by the too-hot summer and too-cold winter.
Although you should carry an umbrella for nine months, you should probably bring a poncho (and a warm coat) if you plan to visit in this cold season now. Winter is the wettest season, so expect fog, rain, even snow. The weather is not great, but it is certainly bearable (and the cheap deals might also give you peace of mind).
Istanbul is slow to warm up. Daily highs won't average above 70 degrees Fahrenheit until May (and even then the average high is about 70.5). You'll find some lingering winter specials on airfares the earlier you visit.
The temperature will read high 70s or low 80s, but you'll think it is much hotter. The humidity is atrocious, and hustling through a dense crowd at a bazaar or waiting in an outside to enter a mosque doesn't help. Brace yourself for muggy conditions and expensive room rates.