Park officials shut down Yosemite Valley over fears that the storm will create dangerous flood conditions.
The Merced River near the park's entrance could rise five feet over its flood stage.
The four inches of rain forecast to fall are not the only problem bringing a deluge of water.
"This is both the rain that will fall, but also it's a very warm storm, and so the rain will fall on the snow. And that will accelerate the amount of water in the river, which will lead to the river rising," said Scott Gediman.
All campgrounds and lodging facilities in Yosemite Valley are now closed until at least tomorrow.