The Leo constellation is visible in the Northern Hemisphere during the late spring and early summer months, specifically from mid-March to early September.

Here's a more precise breakdown:

* Best viewing: Late April to June

* Starts to appear: Mid-March (in the evening sky)

* Disappears: Early September (in the morning sky)

To find Leo:

* Look for the distinctive "sickle" shape of stars that forms the lion's head.

* The bright star Regulus marks the base of the sickle.

* The "mane" of the lion is formed by a backwards question mark shape of stars.

Remember that the exact dates may vary slightly depending on your location and the year. Using a stargazing app can help you find Leo and other constellations in the night sky.