The best time to visit Alappuzha is between October and February, when the weather is dry and temperatures are comfortable (25–32°C). The monsoon arrives in June and lasts until September — the backwaters fill with water and the landscape turns dramatically green, but heavy rain and strong currents make houseboat travel less enjoyable.
The Nehru Trophy Boat Race takes place on the second Saturday of August, right in the monsoon season. If you want to attend, prepare for rain and humidity and book accommodation months in advance.
Onam, the major Kerala harvest festival, usually falls in August or September and is a good time to see traditional snake boat races at various points across the backwaters.