Yep same here Saturday night looked out at sunset to se clear sky for the first time in ages

so out came the gear with the aim of finishing the setup of the new guide scope (ST80) and to do some pointing modelling for the mount.

All went well and I was even running from indoors away from the cold and just peeking out the window to keep an eye on the mount when slewing.
Actually did a couple image runs on the Triffid and also Omega Centauri.

Packed up around midnight like you Malcolm, dew was pretty heavy but the heaters were working very well on the three scopes on the mount but when I turned the outside lights on to pack up I could see the moisture level in the air was very high.
Checked on Sunday morning to find it was rated at 100% humidity all night and we had a frost as well so I understood why my pictures were pretty poor.

Oh well the setup was working well so I was happy with that.
It's gotta improve soon.