UKC

I’ve just got a new altimeter (Suunto Core Crush) and I’ve set it to my home altitude. However over the course of 6hours it’s gained 10m in height. The weather has changed from overcast to sunny. Is this to be expected? 

Definitely. If you’re using it in anger it will need setting at known points during the day if you want it to be accurate.

Yes, I did some analysis once on the weather over a couple of months I found that over a 6 hour window there was greater than50% chance it would drift by over 10m.

if you want it to be more accurate than gps altitude, you need to recalibrate it at summits or known valley altitudes during the day. And always before you start.

It's expected as the altimeter is just a barometer calibrated to show altitude rather than pressure.  This can be useful sometimes as it means you can use the thing as a weather station.

I use a map to ascertain the altitude of our house.  Its much more accurate and every time I look its still at the same altitude. 

(Which is somewhat fortunate as I live near the top of a 200 foot cliff!).

How the f*ckity f*ck did you get a dislike for that?