“Semele’s themes are fertility, grounding, joy, playfulness, pleasure and youthfulness. Her symbols are wine or grape juice and soil. In Greek mythology, Semele is a young earth Goddess who, in mortal form, gave birth to the ever-exuberant party animal Dionysus (the god of wine). Today Semele flows into our lives bringing spring’s zeal, joy, and playfulness carefully balanced with the exhortation to keep one foot firmly on terra firma. Semele’s name translates as ‘land’, giving Her additional associations with fertility and grounding.
Semele became a Goddess after insisting on seeing Zeus (Dionysus’ father) in his full glory. This killed Semele, but Zeus rescued Her from Hades and made Her a Goddess.
A three-day celebration began in Athens around this time to celebrate spring known as Antheseria. The first day of the observance was called the ‘opening of the casks’! So, if you have a favorite wine, today is definitely the time to take it out and enjoy it with some friends. Toast to Semele for giving the world a wine god who lives in every drop poured!
To ‘grow’ any of Semele’s virtues within yourself, find a small planter, some rich soil, and a flowering seed. Name the seed after that characteristic, and water it with a bit of wine or grape juice. If you use diligent care and maintain a strong focus on your goal, when the seed blossoms that energy should show signs of manifesting in your life.”
(Patricia Telesco, “365 Goddess: a daily guide to the magic and inspiration of the goddess”.)
In one version of the myth, Semele was a priestess of Zeus, and on one occasion was observed by Zeus as she slaughtered a bull at his altar and afterwards swam in the river Asopus to cleanse herself of the blood. Flying over the scene in the guise of an eagle, Zeus fell in love with Semele and afterwards repeatedly visited Her secretly. Zeus’ wife, Hera, a Goddess jealous of usurpers, discovered his affair with Semele when She later became pregnant. Appearing as an old crone, Hera befriended Semele, who confided in Her that Her lover was actually Zeus. Hera pretended not to believe Her, and planted seeds of doubt in Semele’s mind. Curious, Semele asked Zeus to grant Her a boon. Zeus, eager to please his beloved, promised on the River Styx to grant Her anything She wanted. She then demanded that Zeus reveal himself in all his glory as proof of his godhood. Though Zeus begged Her not to ask this, She persisted and he was forced by his oath to comply. Zeus tried to spare Her by showing Her the smallest of his bolts and the sparsest thunderstorm clouds he could find. Mortals, however, cannot look upon Zeus without incinerating, and She perished, consumed in lightning-ignited flame. Zeus rescued the fetal Dionysus, however, by sewing him into his thigh (whence the epithet Eiraphiotes, ‘insewn’, of the Homeric Hymn). A few months later, Dionysus was born. This leads to his being called “the twice-born”. When he grew up, Dionysus rescued his mother from Hades, and She became a Goddess on Mount Olympus, with the new name Thyone, presiding over the frenzy inspired by Her son Dionysus.” 
Gill, N.S. About.com, “Semele”
Theoi Greek Mythology, “Semele Thyone“