We have a word which sums up the British weather perfectly, "changeable".
Some years ago I worked for a large import company selling cheap novelties and gift items. One such item was a barometer/clock which was a popular seller wholesaling at around £5. It wasn't untill I dropped one in the warehouse that I noticed that the only working part of the barometer/clock was the battery operated clock, the barometer was just a dial with a glued-on plastic needle set to "changeable".
I have often imagined how many people have tapped the face of their barometer/clock uttering "Changeable again Doris!, we'd better take an umberella, just in case!"
In the U.K. there's not a more accurate barometer!
C-flat.