Thats unusual, it normally moves but from what I have seen its max 20% or so from evening until next day
I usually do a refresh mid evening to see the following day and thats generally good enough
There is quite a band of rain working its was across teh UK today, I think in teh east we will just about avoid it impacting todays generation but pretty much most of the country are likely to see generation cut well down today i think
Do you go directly to solcast or is it imported? Maybe if imported it hadn't updated?
I’m using forecast.solar and importing into home assistant…. All updating fine.
Might try running both solcast and forecast.solar to see which gets it right more often.