The temperatures have been record-breaking outside, but the real heat wave begins this weekend—astrologically, that is. On Saturday, the Sun departs watery, sentimental Cancer and enters majestic fire sign Leo, the sign that it rules. The shift is literally like night and day. Lunar Cancer is the shy, side-scuttling crab governed by the moon, while Leo is the bold, fearless Lion sharing warmth and solar power with the world.

During Leo time (which lasts until August 23rd), those shy and demure summer days give way to grandiosity, big promises and a splash of ego. Whereas we tend to underestimate ourselves under Cancer's reign, Leo has the opposite effect. Everyone's making big promises, whether or not they can back them up. That's not necessarily a bad thing. As the saying goes, sometimes you have to throw your hat over the wall, THEN figure out how to get it. With a shot of courage from the Leo sun, we're up for the challenge!

Leo rules the zodiac's fifth house of passion, theater, creativity and fertility. It's the space of childlike wonder, awe and exuberance…unbridled expression of our hearts' desires. Leo if playful and affectionate, like lion cubs wrestling for sport. And of course, the proud lion loves to be admired, especially for his mane. Try a new hairstyle or add some glamour to your look! Say "yes" to the dress, or to dancing under the stars. Revelry and luxury are Leo's domain—this sign loves to entertain in style, like Leo Martha Stewart.

How to get the Leo party started? We're loving the blog The Sagittarian Mind, especially since blogger Jason Fleming created a special entry called The Leo Mixtape, with a hot selection of some great '90s hip-hop to celebrate the festive Leo month. You'll have to download his playlist suggestions yourself, of course, but we have definitely shaken our Sag booties to many of these hits throughout the years. Put a few on your iPod and take a little dance break. Or, if you happen to be on Team J.Lo, spin a hit or two from the newly-single Latin Lionness's new album in solidarity!