Kathmandu's weather and temperature widely varies through the year. The winter are very cold and harsh to a mostly cool summers.  The monsoon gets a lot of rain and falls between July and August. The wet summer and monsoon means the following months are very green and lush.
The month of September to November is great time to visit Kathmandu as the rain is gone and the weather is generally very pleasure. Its great time to walk around the city and visit its historical sites and the outlining areas for picnics.
Average Weather through out the year:
The months between November to February randge between mid 20's to sub 0°C temperature.
The months April, May and October are the most pleasent with temp ranging between mid 20's to mid 10°C.
The months June, July and August are the hostest with the temp climbing upto mid 30's during the day.

March: Range between 22°C - 10°C
September: Range between 29°C - 22°C
Weather Forcast