When April blows his horn, It's both good for hay and corn.

April’s horn represents thunder. The proverb welcomes the rain that commonly accompanies it as beneficial to hay and grain crops.

The saying presents April thunder as a welcome part of the growing season. Its point is the value of the accompanying rain to both kinds of crop.

Use it as a seasonal remark when April thunder and showers are welcomed for their benefit to crops. The horn image gives the thunder a vivid sound, while the emphasis remains on the rain it brings.