 The period from November to February in Thanjavur is pleasant , with a climate full of warm days and cool nights . The onset of summer is from March , with the mercury reaching its peak by the end of May and June . The average temperatures range from 81 ° F ( 27 ° C ) in January to 97 ° F ( 36 ° C ) in May and June . Summer rains are sparse and the first monsoon , the South @-@ West monsoon , sets in June and continues till September . North @-@ East monsoon sets in October and continues till January . The rainfall during South @-@ West monsoon period is much lower than that of North @-@ East monsoon . North @-@ East monsoon is beneficial to the district at large because of the heavy rainfall and the Western ghats feeding the river Cauvery . The average rainfall is 37 inches ( 940 mm ) , most of which is contributed by the North @-@ East monsoon . 
