How often it rains on Christmas
From the Houston/Galveston National Weather Service:
The Ghost of Christmas Past has had to wear galoshes or other rain gear as it rains on Christmas about once every four years. The temperature in Houston typically will reach or fall below 32 degrees about once every 5 years. The coldest Christmas in city history occurred in 1983 when the low temperature plummeted to 11 degrees. The Ghost of Christmas Past was likely wearing sunglasses and sun screen in 1964 when the temperature soared to 82 degrees. The high temperature will reach or exceed 70 degrees about once every five years.