Tokyo lies in a temperate zone, which means that it enjoys moderate and comfortable climate year round.   It is the most comparable to the East Coast of the United States.

Spring lasts from March to May and seems to be an ideal time for sightseeing.  Early spring may still experience some cooler days (where a light coat or sweater is needed), but in late April and May the days are much warmer when only short sleeves can be worn.  Occasional rain showers may occur at this time. Average temperatures range from 2°C to 17°C (35 to 62°F).

Summer starts in June and lasts until August.  This is the hottest time of year when temperatures can exceed 30°C (86°F) with high humidity.  Summer is also the rainy season, particularly during the hot and muggy month of July.  Average temperatures range from 21°C  to 30°C (70 °F to 86°F).

Autumn is from September to November, and is generally cooler with less humidity.  However, if you visit during September there may still be days that reach above 30°C.  Fall is always a welcome relief with clear blue skies and beautiful flowers. Average temperatures range from 13°C to 26°C (56°F to 78°F).

Winter is from December to February, characterized by chilly and gray days.  Even though temperatures rarely fall below freezing, snow showers occur from time to time in the center of the city (even though it rarely piles up).  Days are short with sunset around 5:00pm.  Average temperatures range from -1°C to 9°C (29°F to 48°F).

The best times to visit Tokyo are during the more temperate months of spring and fall.  

Official weather and forecast information from the Japan Meteorological Agency for the Tokyo area is available online; temperatures are given in Celsius.

Tokyo, Japan Weather - 5 Day Forecast