An estimated 200,000 people are expected to gather in downtown Washington, D.C., on Saturday for the U.S. Army’s 250th birthday parade, but unsettled weather could bring showers and storms.

The National Weather Service forecast for Washington D.C. on June 14 has a 50% chance of rain, with thunderstorms possible.

For its 250th birthday, the Army put on the largest show of military might in the capital in more than three decades.