I don’t ever wear sandals, but up north I think it’s a fashion faux pas to wear them between Labor Day and Memorial Day anyway.
My personal way to dress for cold (assuming no rain/snow falling, which would lower the criteria):
60s – no extra layers unless it’s very windy (it’s warm in the sun, but may feel chilly in the shade in the low 60s with wind, so I’d bring a light jacket)
50s – light jacket
40s – light jacket if outside for short time, hat and coat if outside for a longer time (e.g., walking to shul on Shabbos), add gloves and earmuffs if windy.
30s – coat if outside for short time, add hat, gloves, earmuffs if outside for a long time or windy.
20s – coat, hat, gloves, scarf, maybe warm boots
10s – same, definitely warm boots, also add thermal pants if outside for a long time and windy
Single digits – same, add thermal shirt if windy, try to cover my face with my scarf
Below 0 – Extremely rare in my area, not safe to have exposed skin outside for long, especially if windy. Would wrap scarf around my face, or get a face mask. Possibly wear a second thin layer of gloves under my normal gloves.