The Anglo-Saxon Lunar Calendar

The Anglo-saxon lunar calendar gave names to the full moons of the year based upon the season in which they fell, e.g. the first full moon after the winter solstice is the Moon After Yule, and the first one following the spring equinox is the Egg Moon. The full list of full moon names is shown in the table below. These, with the exception of the Moon Before Yule and Moon After Yule follow those generally accepted as being the Old English names, and as named in this Wikipedia article.

Full Moon Name Date Range
Moon After Yule Dec - Jan
Wolf Moon Jan - Feb
Lenten Moon Feb - Mar
Egg Moon Mar - Apr
Milk Moon Apr - May
Flower Moon May - Jun
Hay Moon Jun - Jul
Grain Moon Jul - Aug
Harvest Moon Aug - Sep
Hunter's Moon Sep - Oct
Blood Moon Oct - Nov
Moon Before Yule Nov - Dec

To keep the moons in line with the seasons, however, an "extra" moon has to be inserted every now and then. Each season normally has three full moons, but when a season has four full moons, the third one is designated as the "extra" moon. This ensures that certain full moons, such as the Moon Before Yule and the Egg Moon, which must occur at certain times, are not displaced. This extra moon is called the Blue Moon. This article in Sky & Telescope claims that this rule is the correct and traditional method of defining a blue moon, and it is the method adopted here.

The full moons for the years 2013-16 are shown in the table below.

Moon 2013 2014 2015 2016
Moon After Yule 28 Dec 2012 16 Jan 2014 5 Jan 2015 25 Dec 2015
Wolf Moon 27 Jan 2013 14 Feb 2014 3 Feb 2015 24 Jan 2016
Lenten Moon 25 Feb 2013 16 Mar 2014 5 Mar 2015 22 Feb 2016
Egg Moon 27 Mar 2013 15 Apr 2014 4 Apr 2015 23 Mar 2016
Milk Moon 25 Apr 2013 14 May 2014 4 May 2015 22 Apr 2016
(Blue Moon) - - - 21 May 2016
Flower Moon 25 May 2013 13 Jun 2014 2 Jun 2015 20 Jun 2016
Hay Moon 23 Jun 2013 12 Jul 2014 2 Jul 2015 19 Jul 2016
Grain Moon 22 Jul 2013 10 Aug 2014 31 Jul 2015 18 Aug 2016
(Blue Moon) 21 Aug 2013 - - -
Harvest Moon 19 Sep 2013 9 Sep 2014 29 Aug 2015 16 Sep 2016
Hunter's Moon 18 Oct 2013 8 Oct 2014 28 Sep 2015 16 Oct 2016
Blood Moon 17 Nov 2013 6 Nov 2014 27 Oct 2015 14 Nov 2016
Moon Before Yule 17 Dec 2013 6 Dec 2014 25 Nov 2015 14 Dec 2016