Temperature Data Collected by Japan Meteorological Agency
 

I would visit Hokkaido in summer. :)

You can check out Monthly Mean Daily Maximum Temperature in Niigata. It was 25.9 degrees C in July and 30.9 in August last year.

Monthly Daily Maximum Temperature in other northern cities in July and August 2007

Tohoku
Fukushima 福島 25.9 31.9
Sendai 仙台 23.8 29.9
Yamagata 山形 26.1 31.6
Morioka 盛岡 25.3 28.8
Akita 秋田 26.4 29.2
Aomori 青森 25.1 29.6

Hokkaido
Hakodate 函館 22.2 27.1
Sapporo 札幌 24.2 28.3

I'm thinking how far from the trip I should buy my tickets. I know the farther away from the departure date the cheaper they are but I'm still not sure when I should buy the tickets if I'm leaving in late-May.

coolers at 24C? Departments stores, movie theaters and supermarkets felt like meat lockers in Japan. Shopping in Osaka in summer, I actually got a little woozy from going from 35C to (seemingly) freezing temps inside stores and back again.

oh jeeze i remember Tokyo last 2 summers.

Id take a shower get dressed and walk one block down the road and be soaked in sweat =P

makes shopping a hassel, and i always end up going back to my apartment for showers and gettin changed

I am going to Japan this summer on a trip with my family. What should I do to prepare for the heat?

Is it like that in north Honshu and Hokkaido also?
That you get soaked in sweat?

I have learnet the the temperature is a little lower in the north, but do we have anyone here who have spent the summer in Hokkaido or anyone who knows if it´s cooler there and if u get soaked in sweat there also :)

I really need to know if it´s a difference in the climate in the north compared to Tokyo. I will spend a lot of money to travel to Japan and I don´t won´t to waste it to get soaked in sweat :) So should I go or not to north of Japan in the summer?

I have been in Hokkaido in the summer, and yes the weather is a little more tolerable, but I wouldn't want to spend my entire vacation in Hokkaido (and there isn't that much north of Tokyo). If you are that averse to hot weather, I might think about choosing another country.

Go to Hokkaido!
 

You wouldn't get sweaty unless you start running around. It's not that hot. The summer in Hokkaido doesn't last long and is more like autumn by Honshu standards. In fact, South Sweden and Hokkaido belong to the same climate zone Dfb (Warm Summer Continental or Hemiboreal Climate) according to the Köppen-Geiger climate classification. Tohoku and the Central Highlands have Dfa (Hot Summer Continental Climate) and the rest of Honshu Cfa (Humid Temperate Climate). People in Honshu go to Hokkaido to escape from heat and enjoy hiking, cycling and camping from June to September.

Sapporo has big city attractions. Hakodate is known for the spectacular night view from Mt. Hakodate. Furano in central Hokkaido is known for lavender and flower fields. These are the cities I would visit, although I have visited Asahikawa and Kushiro in August as well. I have a friend from Asahikawa. ;)

Hokkaido has a number of national parks: Daisetsuzan, Shiretoko, Rishiri, Rebun, Lake Toya, Lake Akan, and Onuma. I can provide links to pictures of Hokkaido if you want.

In short, you should go!:ywave:

Hokkaido Travel Guide here

:) Thanks for your very detailed help!
I´m much more confident now that it will be fine.

I just red about some other guys from Sweden who traveled around Tokyo in summer 2007. They thought it was a little hot but they had a really nice travel.

From what I know now I think I have decided to book the tickets :)

My plan is to start in Tokyo and then travel north along the west coast and then up to Hokkaido.