In July 2018 Kumagaya recorded 41.1 degrees Celsius, then the highest temperature ever measured in Japan, and the city wears the title of hottest town with something like pride. Banners proclaim it, shops sell heat-themed souvenirs, and in summer the town fills with misting stations. If you are riding through in July or August, take the heat seriously: drink constantly and avoid the middle of the day.
Kumagaya lies on the north bank of the Arakawa, in the flat plain of northern Saitama. In spring the river embankment is lined with cherry trees, and the town fills with people picnicking under the blossoms. The Uchiwa Matsuri, a big summer festival in July, features floats, drums and crowds.
There is no good swimming nearby. The Arakawa is a broad river with strong currents and a stony bed, and while people paddle at the edge in summer, it is not safe for swimming. The town has public pools, which are a better option on a hot day.
Gyōda, a little to the east, has one of Japan's most important groups of ancient burial mounds, the Sakitama Kofun, with large keyhole-shaped tombs from the fifth and sixth centuries. An iron sword found in one of them bears an inscription in gold that is one of the oldest written texts in Japan. Gyōda also has the reconstructed Oshi castle, which held out against a siege in 1590.
The riding is flat and straight, with busy national roads and heavy truck traffic. Route 140 heads west towards Chichibu and the mountains, where the riding becomes much more interesting. Shaved ice has become the town's edible answer to its own climate, and in August there is no more sensible purchase. Pumps and konbini are everywhere along the main roads.