Planning for the weather is an important factor for making your trip to Siddharthanagar a success, especially when you’re splurging. The hottest months are usually May and April with an average temp of 88°F, while the coldest months are January and December with an average of 67°F. The rainiest months in Siddharthanagar are July, August, June, and September, with each month seeing an average of 15 inches of rainfall.