November to February is the best time to visit. Coastal Gujarat is pleasant at this time — warm during the day, cool at night, and dry — and the migratory birds at Khijadiya are present in force.
March to May is hot, often above 35°C, and the humidity from the Arabian Sea makes the afternoons hard work. Morning sight-seeing and a long lunch indoors is the survival strategy.
June to September brings the monsoon. Heavy rain, occasional flooding, and the marine park largely inaccessible. The countryside is greener than you would expect from the dust of summer, but most visitors save Gujarat for the dry season.
The Janmashtami festival in August/September is celebrated with particular vigour in Dwarka, 130 km west — worth timing a visit around.