The park is unique in nature, making it difficult to specify any particular time as being the best time. Kanha has three major seasons - the rainy, the cold & the hot.
The rainy season (Mid June - October) :
The monsoonal showers in late June kills the heat & the vegetation turns into intense green. A thick undercoat starts covering the forest floor & the leaves on the decidous trees unfold. This the fawing period for the herbivores. But the park is closed for visitors in this season.
The cold season ( November - February) :
Winter is the best season of the year. The day temperature rarely goes over 30°C. November is mildly cold while December - January are the coldest. Since monsoon has recently receded the vegetation is green, but the grass in the meadows turns yellow due to severe frost.
The hot season ( March - Mid June) :

Summer in Kanha is not very harsh. Though the daytime temperature reaches 40°C in shade, there are no hot winds. rains, if any are sporadic, but it sometimes hails in March - April. This coincides with the rutting season for Chital(Axis axis). The meadows are filled with dominant stags displaying and courting with the females and fighting rivals for them.

Most of the people prefer to visit Kanha between February & June. A stay of 3-4 days is advisable to get a really good sighting of Kanha's entire range of wildlife.