We were there that week too, but we are from Michigan so it was warm
Down parkas? Don't make me laugh. It was cool in the morning, but we are old geezers and don't do early AM rope drops. By 9 AM when we got to the parks, it had already warmed up a bit. I layered a t-shirt under my shirt short sleeve shirt and brought a travel blazer to wear when it was chilly. Most of the time it was rolled up in the day pack. Thursday that week was the chilliest (went to the long sleeve shirt). Take note of the wind. That more than the temperature made the difference for me. Thursday was quite breezy and that made it feel feel much colder. Also in the early evening there always seemed to be a time when the wind would pick up for an hour or so (around 7 PM?) but then it would calm down after that. On Monday we were on the outside patio at Spice Road Table when the early evening breeze kicked in. We weren't sure if we were going to enjoy our perfect Illuminations view table until the 9 PM show. But then the wind died down and it was fine (for us).