
Previously I've stopped feeding when it's dropped below 10 degrees, last couple of years though I've not checked and just gone by feel and fish behaviour as they don't tend to come up looking so much when it's getting colder. I don't gradually decrease the amount but I don't feed daily anyway, but once or twice a week (big pond, lots of bugs and stuff in there for them to eat and I find the water quality is better for them if I don't feed as often).
If the weather warms up for a day I won't feed, if weather forecasts all suggest it'll be a short period or warmness I might do - the problem is the food sitting in the gut after the tmep drops and not being digested, so I'll only feed on the first day of a warm spell so they have time to digest.
In spring - opposite of now, really: when I see them start to come up looking and when it warms up pretty consistently, I'll feed.