from Upāli Thein, Bagan, Myanmar
This is the calendar for the new monastic year of 2015/2558. This year is a ‘leap year’, which requires an additional month to be added in. The Thais adjust their calendar earlier than in Myanmar and Sri Lanka they therefore celebrate Vesākha one month later than the former, on June 1st, rather than May 2nd.
As always the Dhammayut sect’s calculations differ from the others, but even after making this calendar for many years I have never found anyone who can explain how they make their calculations, and why they come out different to everyone else (if someone reading this knows, then please put me out of my misery).
For more information on the way the calendars are calculated see here.
Updated, 30th December to show the Chinese Calendar, which is based on astronomical calculations and is used by the Mahāyāna and many of the Theravāda monasteries in Malaysia for dating the new and full moons.
to calculate monastic dawn and midday anywhere in the world
and get a full year chart for your area, see this page.