Pretty bad when they have to manipulate…..
check it out:

Weather agencies in Australia, Paraguay and Switzerland may be manipulating temperature data to create a sharper warming trend than is present in the raw data — a practice that has come under scrutiny in recent months.

Most recently, Dr. H. Sterling Burnett with the Heartland Institute detailed how the Swiss Meteorological Service adjusted its climate data “to show greater warming than actually measured by its temperature instruments.”