How many well defined seasons does Japan have?
It is a common Japanese myth, based on Chinese literary
traditions, that Japan has four seasons. In fact, it has five (5).
The so-called 'rainy season', (or 'Tsuyu', etc.), which in most of
the country lasts from mid-June to the end of July, is in fact the
tail-end of the Asian monsoon. Temperatures drop from late May, and
the frequency and intensity of rain gradually increase, until, by
late July, hot and heavy rain is falling. The 'Tsuyu' is definitely
a distinct season, which every year causes deadly landslides. This
is most people's least favourite season.
'Summer proper' ('honkakuteki na natsu') does not begin until
the end of July or early August. Summer --with its heat and
typically Asian high humidity-- then continues right though
September and even into early October. In central and western
Japan, Autumn leaves do not turn or fall until late
October-November, and some remain on the trees until Christmas. It
follows that the other seasons are likewise skewed, Winter not
beginning until late December, Spring lasting through to early May,
the Tsuyu following, and --once again--Summer not beginning until
late July-early August.
All of the four 'normal' ones.