Japanese Summer — How Long, How Hot & How to Survive!

Published June 3rd, 2021

We're almost in the middle of the year, which means that the weather's going to warm up. Whether it's to have a dip in the ocean or lie on the soft sand, summer's greatly anticipated. Japan's summer, though, is no joke. Not only is it packed with events and festivals like neighbourhood matsuri (祭り) and music shows, but it's the peak of heat and humidity.

You hear a lot of people talk about Japanese summer and how hot it can get here. How hot are we talking about? I'm telling you, it really is, coming from a girl who grew up on a tropical island.

So before you get packing for your next Japanese summer trip, here are some things you need to know.

People at a summer street festival in Japan.

Image Credit: Kentaro Toma

Natsu (夏) in Japan is something everyone should be talking about. I personally have never experienced humidity like this. And like I said, I grew up in tropical Singapore, so I didn't think anything could be worse than that.

Japanese summer starts around June and lasts all the way till August. It's roughly three months, but it can vary depending on exactly which part of Japan you're in. There's also global warming, so summer can start as early as late May and last as long as mid-September.

If you find yourself in the southernmost part of Japan, like the Kansai region and Okinawa, you're going to get a longer summer. Don't forget the humidity as well. The Kanto region, where the capital city Tokyo is, is not too far off the heat and humidity levels, too. However, if you're up north in Hokkaido, you not only get a shorter summer but also the cool and not-so-humid weather. That's why lots of locals travel up north during this time!

If you're wondering where you should spend the summer in Japan, Tokyo's your best bet. Here is where you get all the great festivities and events.

Don't worry if you're early for Japanese summer. Late May and early June are the best times for flower viewing. Hydrangeas bloom everywhere, along with some other summer florals. Kamakura's Meigetsuin Temple is famous for its blue hydrangea garden.

Be prepared with umbrellas, though. The start of summer in Japan is also the start of the rainy season (tsuyu, 梅雨). You might even get a typhoon (taifu, 台風) or two. The rainy season can be a week of non-stop rain and strong winds, usually at the end of June to the start of July. You might want to avoid these dates if you're not a fan of the rain.

Summer Temperature in Japan

Large crowd at a summer festival at a shrine in Japan.

Image Credit: Julie Fader

The temperature in Japan during the summer can fluctuate. One day it can be a great summer's day, and the next it can be as unbearable as it can get. Some of my Japanese friends have noted that summer temperature in recent years has been particularly high. We're advised to take precautions so as to not get heatstroke.

June's weather is comfortable. You'll get a cooling 22ºC in the afternoons and it drops to about 18ºC in the evening. Since it's also approaching the rainy season, you can expect a few rainy days. Pack an umbrella!

It warms up in July after the rainy season. You get 22ºC evenings and warm and humid 28ºC afternoons.

Nothing beats August. It's the hottest month of the year. 31ºC afternoons are conservative. It can go as hot as 35ºC for a whole week or two. Sunscreen and a bottle of cold water are going to be your best friends.

Summer Humidity in Japan

Japanese Lanterns

Image Credit: Atul Vinayak

Sure, you can gauge the heat in Japan from the temperature, but it's the humidity that gets you. You see everyone's dressing going from chic to casual in a matter of days.

Some say it gets humid in June, but I say it's already slightly humid in late May. June's humidity level is at an average of 75%. The previous month's humidity levels are 60%-65% on average. That's quite a big jump from spring to summer.

July is looking at 79% humidity. It's especially humid after the rainy season. August's humidity level drops to 73% as it gets closer to autumn, but combine that with the hot temperature and you get the hottest month of the year. Don't avoid August, though. It's the month of festivities and events. Just pack a few caps and sunglasses.

Now you know. Japanese summer can get not only pretty hot but humid as well. What do you think, will you still be visiting the country during the summer? The Japanese festivities are a once-in-a-lifetime experience, so it's a lose-some-win-some situation, I might say. Don't get scared off by the Japanese heat!