Full Moon Calendar 2021

It's a supernatural delight, everybody's swimming in the moonlight

Benjamin Child

Swimmers are the latest in a long line of tribes to use full moons as a touchstone for seasonal change. Full moon swims can be a way to observe the shift of the seasons and give your foray into water a fresh motivation.

The dates of each moon are listed below, while OSS team member Owen Hayman explains why his swimming group, the Sheffield Outdoor Plungers (SOUP), never miss a full moon swim and gives some tips to make the most of the night.

January: Wolf Moon

Thursday 28th January,  19:16 UTC

Also referred to as the Moon after Yule and the Old Moon, Wolf Moon originates from hungry wolves howling outside villages late at night at this time of year. This year’s wolf moon coincides with a lunar eclipse, so worth looking out for!

February: Snow Moon

Saturday 27th February, 08:17 UTC

Named after the snow that is normally on the ground in February in the norther hemisphere, Northern American Tribes also name it the Hunger moon, when food sources are scarce and the hunting conditions are difficult

March: Storm Moon

Sunday 28th March, 18:48 UTC

The arrival of spring with the March full moon has generated different names across the world: among them the Sap Moon, Worm Moon, Chaste Moon (symbolising the purity of early spring), Crow Moon, Warming Moon and Moon When the Leaves Break Forth.


April: Full Pink Moon

Tuesday 27th April, 03:31 UTC

Also called the Budding Moon, Full Melting Moon, Moon Where Ice Breaks In The River (Arapaho tribe) and Fish Moon (as fish begin to swim upstream).


April is the first of two supermoons in 2021. A supermoon is when the moon is at perigree – the point at which the moon is closest to the earth and therefore appears larger.

May: Big Leaf Moon

Wednesday 26th May, 11:13 UTC,

Also called the Blossom Moon, Full Flower Moon, Corn Moon, Hare Moon and Milk Moon, May’s full moon is the second and final supermoon of 2021, and signifies the month when leaves and blossom burst into life, when corn is ready for planting and when cows are ready to milk more frequently.

June: Hay Moon

Thursday 24th June, 18:39 UTC

Also known as the Hot Moon, Honey Moon and Full Strawberry Moon as it is the time to cut hay, pick ripe strawberries, and where the moon takes the lowest arc across the sky, which makes its have a glowing yellow hue.

July: Thunder Moon

Saturday 24th July, 02:36 UTC

Also known as the Buck Moon, this is the season for thunderstorms and when new antlers emerge from buck’s foreheads.

August: Hungry Ghosts Moon

Sunday 22nd August, 12:01 UTC

Under the full moon, people light lotus-shaped water lanterns and float them on lakes, rivers, and pools, in order to provide light for lost souls to find their way safely back into the afterlife. Also known as the Sturgeon Moon as Native American Tribes knew this was when Sturgeon were most common in the Great Lakes.

September: Big Moon

Monday 20th September, 23:54 UTC

September’s full moon has a tendency to look brighter and bigger than others in the year, its luminosity and brilliance earning it the name Big Moon by Native American tribes, more commonly called Harvest Moon in the UK.

October: Moon When Rivers Start to Freeze

Wednesday 20th October, 14:56 UTC

The Blood Moon or Hunter Moon rises early in the evening, which means that you are more likely to see it near the horizon – like September’s moon, this creates the illusion of it being bigger. It also scatters more blue light, letting more red light reach your eyes.

November: Reed Moon

Friday 19th November, 08:57 UTC

Though not the origin of the name, silhouetted reeds are likely to accompany late October and November river swims. Also called the Mourning Moon by pagans:  “For the Pagans, on the other hand, the final stage of their winter preparations involve the very important process of “mourning” – which is why they call the last moon before the winter solstice the Mourning Moon. After a full year of accumulating possessions, both physically and otherwise, the Mourning Moon is the perfect time to let go of old, unnecessary things, while giving yourself permission to mourn their passing. Practicing Pagans may perform a moonlit ritual where they write down the things they want to rid themselves of, and ask their Goddess for help in removing unwanted burdens.” Also known as the Beaver Moon, Trading Moon and Frost Moon, as it is when Beavers are busy building their winter dams in preparation for the cold season, when stock prices tend to be lowest and when the first frost commonly occurs.

December: Cold Moon

Sunday 19th December, o4:35 UTC

Also called the Full Long Night’s Moon, Moon before Yule and Oak Moon as the Oak is a symbol of strength and eternity and to survive through winter we need to emulate that strength!


  • For information on the practical elements of night swimming, see Lynne Roper’s classic piece on Moon Gazey Madness.
Photo by Quino Al on Unsplash

“Swimming on a full moon is almost a ritual in SOUP. We like to swim at full moon because night swims by themselves can be a lot of fun. For people swimming through winter and wanting to swim more often than just weekends, there is little option but to swim in darkness on a weeknight.

“A full moon not only brings with it the possibility of the darkness being brightened with the light of the moon, but it also sets an astronomical date on which to swim, so it definitely happens and can be planned in advance. It removes all the umm-ing and ah-ing about setting a date. 

“The hope of seeing the moon shining bright in a clear starry sky, and silver shimmering on the water, is enough to entice those to the water who would otherwise struggle to give up an evening snuggled in front of the TV. The fun names of all the different full moons through the year are also a useful marketing tool to help us motivate people to join us on a swim. Who doesn’t want to swim under a Strawberry Moon?!

“Doing a bit of preparation is important. You wouldn’t believe how many ‘full moon’ swims I’ve been to where the moon wasn’t even above the horizon, or it wasn’t even dark enough to get the benefit.

“To help ensure the best chances of actually seeing the moon on your swim, check where the moon will be in the sky, and make sure you swim at a time when the moon will actually be high enough from the horizon to see it. It is not safe to assume that just because it’s dark the moon will be visible. You can use the moonrise and moonset calculator for any given location, to see where in the sky the moon will be at a given time. 

“If you’re unsure what the degrees mean on the moon calculator, use this hand tool. It will help you visualise how high the moon will be in the sky. Look up your swim spot on Google Maps and then use the compass to see what direction the moon will be shining in from, according to the directions on the moon calculator.

“You’ll also need to check it’ll actually be dark! In winter this is generally not a problem, but in summer you will need to look at when it will really be dark enough for that full moon glow experience. Sunset time alone isn’t enough, you need to look at the different levels of twilight and when ‘night’ actually starts. This is a good guide.

“In general, think about aspect and things like big hills and tall trees that may shield you from the best view of the moon. Just like catching a good sunset, you want to pick the best time and location to see the moon shining over the water while you swim.

“Finally, in winter especially, having an open fire is a huge bonus. We take a small fire-bowl and wood in a wheelbarrow so we can have the warmth of a fire while leaving no trace.”

Owen Hayman, member of The OSS Inland Access team, and a coordinator of SOUP (Sheffield Outdoor Plungers).