Myanmar has a total area of 678,500 square kilometres (262,000 sq mi), with a length of 2,204 kilometres (1369,502 sq mi), and most of the country is lying within the tropics. Therefore, the country is located in the monsoon region of Asia with its coastal regions receiving around 5,000 mm (196,9 in) of rain annually. The country has 3 distinct seasons, the hot season going from February to the end of May, the rainy season, starting in June and ends in September, and the cold season starts in October and ends in January.
The best period to visit the most of Myanmar is from November to February because of the breeze, making the weather cooler, and the vegetation after the rainy season will amaze you. On the other hand, March to May are extremely hot especially around Bagan and Mandalay.
During this season, temperatures rise above 30 °C (86 °F) in the whole country, and even in few regions, mainly in the centre part of the country, heat may reach 40 °C. April is the aridest month of the season.
May is the end of the dry season and the begging of the rainy season. In the middle of the month, the monsoons bring heavy rainfall in southern regions, so note that if you want to visit Myanmar during the Spring, coastal regions are the best to visit. Another option would be to visit higher regions in the North-West mountains.
The temperatures are not changing drastically, the changes are mostly felt in central regions where the temperatures drop around 35 °C (95 °F).
During the rainy season, the landscapes are changing, things get damp and when there is a heavy downpour, drains get flooded with water and the roads are blocked. However, the rainy season is Myanmar people’s favourite season mainly because it brings rain to the plants and vegetation. It is a considerable help for farmers. You will notice that even dry areas like Bagan get greener than usual. In opposition to the dry season, some regions are inaccessible, mainly the coastal region due to the strong winds and heavy rains.
If you visit Myanmar during this time, you will find a different country, a luxuriant country.
December is in the middle of the cold season and is the best month so far. January is characterised by a drop of temperatures and even in the centre, you will get lower temperatures.
This season is the best season to visit Myanmar, temperatures are not above 30 °C and the vegetation after the rainy season will amaze you.
Note that February marks the end of the cold season and at the end of February the arid season it totally back.