Calendar rarity · Europe/London rule

When is the next Blue Moon?

The next monthly Blue Moon in UK local time is Sun, 31 Dec 2028, reaching full phase at 31 December 2028 at 16:48 GMT.

The monthly definition used by this calendar

This site calls the second full Moon in one Europe/London calendar month a Blue Moon. Time zone matters: an instant close to midnight can belong to a different civil date elsewhere, so a UTC list can occasionally disagree with a UK calendar.

The phrase does not describe colour. A genuinely blue-looking Moon is a separate, unusual atmospheric effect caused by particles that filter light.

Long-range calendar

Upcoming monthly Blue Moons

Sun, 31 Dec 202831 December 2028 at 16:48 GMT
Tue, 30 Sept 203130 September 2031 at 19:58 BST
Mon, 31 Jul 203431 July 2034 at 06:54 BST
Sat, 31 Jan 203731 January 2037 at 14:04 GMT
Tue, 31 Mar 203731 March 2037 at 10:53 BST

The older seasonal definition

Another rule calls the third full Moon in an astronomical season containing four a Blue Moon. It is not interchangeable with the monthly rule. For example, the next seasonal Blue Moon is Thu, 20 May 2027, while the next UK-monthly one is Sun, 31 Dec 2028. The calendar uses the monthly rule consistently for year counts and badges.

20 May 2027 at 11:59 BST — third of four full Moons in the season
24 August 2029 at 02:51 BST — third of four full Moons in the season
21 August 2032 at 02:47 BST — third of four full Moons in the season
22 May 2035 at 05:26 BST — third of four full Moons in the season
18 May 2038 at 19:23 BST — third of four full Moons in the season

Calendar boundary method