The warmth attracts minnows and you know the rest. A few scattered weeds growing up between the rocks can be a real bonus. Massive bait schools break up and walleyes head for specific structural elements that funnel scattered, roaming forage past specific spots. Look for long fingers or spines that protrude toward the main lake. Roaming baitfish usually congregate along these fingers and filter down them.
Walleyes wait at the tips.
Find those spots and you'll find big walleyes. Bright warm days are preferred to cold, blustery ones. The sun is lower in the sky this time of year, so light penetration is decreased. However, bright days will cause the water to warm up, which will turn fish on. Frequently, action will be better from mid-day on.