It can go either way. The evenings are already cool in Jerusalem, and the days not boiling hot anymore. See if you can wear something "all season" with layers. I wouldn't wear completely winter. And we haven't needed coats yet at all.
Succos weather in Israel often calls for regular Summer wear, with a sweater for the evenings. If you have a lightweight knit outfit, you shouldn't be too hot in that. Velour might be excessive.
The no white thing is less of a rule here. I think one piece of an outfit is ok. Maybe black and white mixed into a print. A fully white dress or outfit might be too much. White shorts for children might seem too Summery.
It's definitely not winter here. Not in the slightest.
Jerusalem weather in the Fall is pretty warm during the day and and a sweater at night type of weather.
