The Twins · May 21 – June 20
May 31 Zodiac Sign
Born on May 31, you're a Gemini — curious, witty and endlessly adaptable — the zodiac's great communicator.
Zodiac sign
Element · Modality
Air · Mutable
Decan (second)
Mars-ruled
Birthstone
Emerald
Birth flower
Lily of the valley
Season position
Day 11 of 31
What astrology says about a May 31 birthday
May 31 is day 11 of Gemini season, so astrologers link it with the sign's core character: curious, witty, adaptable, social. Traits astrologers commonly associate with Gemini include excellent communicator and storyteller; adaptable and comfortable with change; social, friendly and easy to talk to.
A commonly cited growth area for Gemini: avoiding deep emotional conversations. For the full picture of the sign, read the Gemini guide.
2nd decan of Gemini: Mars
Each sign is divided into three decans, 10° slices that the Sun crosses in about ten days each. May 31 falls in the second decan of Gemini (about May 31 – June 9), which the traditional Chaldean system assigns to Mars. Astrologers say that adds drive, courage and a direct approach.
Mars makes this stretch of the sign more assertive and action-minded — these are people who move first and think about the details on the way.
The number 31 in numerology
The 31 combines the 3's expressiveness with the 1's initiative. A birthday on the 31st is linked to practical creativity and the drive to turn ideas into results.
Numerology is a separate tradition from astrology and is offered here for interest.
May birthstone and flower
The modern birthstone for May is Emerald and the commonly listed birth flower is the lily of the valley. May falls in late spring in the north and late autumn in the south.
Gemini love and compatibility
For Gemini, attraction starts in the mind. They fall for good conversation, clever banter and someone who can keep up with their many interests. Variety, spontaneity and shared curiosity keep a relationship alive.
Astrology is a symbolic tradition, not a science, and interpretations vary between astrologers. This page is for reflection and entertainment, not prediction or advice.
Beyond your May 31 Sun sign
Your Gemini Sun is one planet. Your Moon, Rising sign and the exact Mars-ruled decan details live in your full natal chart. Get yours free on Skygram.
Get my free birth chartMay 31 birthday FAQ
What zodiac sign is May 31?
May 31 falls in Gemini, which runs from May 21 to June 20 in the tropical zodiac. The Sun changes sign at a slightly different moment each year, so the boundary can fall a day or so either side of these dates. If you were born close to the edge, your birth year, time and place decide it.
Is May 31 a cusp birthday?
Not by the usual definition, which counts the first and last couple of days of a sign. May 31 is day 11 of Gemini season, so it is normally read as a clear Gemini birthday.
Which decan is May 31?
May 31 is in the second decan of Gemini (May 31 – June 9). In the traditional Chaldean system this decan is ruled by Mars, which astrologers say adds its own flavour to Gemini. Some modern astrologers assign decan rulers by element instead, which gives different planets, and decans are strictly 10° slices of the zodiac, so the date range is approximate.
What are the birthstone and flower for May?
The modern birthstone for May is Emerald and the birth flower is the lily of the valley. These come from calendar tradition rather than astrology, and the lists vary by country and source.