The months of March to June is when temperature is bit high. There is not much iation in the temperature, with the minimum temperature ranging around 22 degrees celcius, while the maximum temperature is around 35 degrees celcius.
The monsoon is during July to September. The weather is pleasant during this season.
The winter is during October to February. This is the best season to visit Trivandrum. The minimum temperature drops down to 15 degrees.