This saying comes from an English proverb that describes typical March weather as:
- "March comes in like a lion and goes out like a lamb."
In the 19th century it was used as a prediction contingent on a year's early March weather:
- "If March comes in like a lion, it will go out like a lamb."
I'm not sure what weather is coming in April but I'm longing for more days of warm springtime sun and new flowers.