The Izu peninsula has a lot to offer when it comes to outdoor activities.  Many of them revolve around water sports but there are many additional possibilities.

The temperature on the Izu is quite mild for most of the year especially in spring and fall and many activities can be done all year with some modification. Snow is fairly rare in winter and the temperature does not dip below zero that often around the coasts although it is a bit colder in the central mountains. Even at the highest point of the peninsula in the Mount Amagi range (1406 meters) there usually only snow for a few days in winter. Winter still does affect what you can do – dry suits for scuba diving, warmer clothes for hiking, biking, etc.  But there is no better time for a dip in a hot spring than after a cold busy day outside.

The rainy season in June is actually not day after day of heavy rain. It is cloudy and rains quite often but there are days where there is no rain or only a bit or rain.

 After the rainy season ends the temperature and humidity ramp up and you need to make sure you stay hydrated especially if you are active.  Some places like the north / south hiking trail that passes by Darumaya are quite exposed to the weather in many spots and you need to take bit more care in summer and winter. Visiting in summer does have the added benefit of the chance to see a number of the local summer festivals. 

The Japan Meteorological Society’s English website  is quite useful to keep track of storms, typhoons, etc.