There's nothing like an all-inclusive holiday in Siddharthanagar to rejuvenate you, especially when you know what kind of weather to expect. Here's some information to help you decide when to book: The hottest months are usually May and April, with an average temperature of 31°C, while the coldest months are January and December, with an average of 19°C. November and December are the driest months, while July and August are the rainiest months.