Quartz, granite or butcher block beside a sunny Riverside window

Ninety degrees at four in the afternoon is an ordinary summer reading in Riverside, and a counter beside a west window sits in direct sun for hours of it. A dark surface climbs well past the air temperature, which is why the figures kept at riverside kitchen remodeling milestones calendar for kitchen layouts treat window position as a material question. The counter choice matters more in Riverside, CA than the color chart suggests.
What does sun do to quartz?

Engineered quartz is mostly crushed stone held together by a resin. The stone does not care about sunlight. The resin can yellow slightly under long, direct exposure, and light colors show it first. Quartz also tolerates heat less than natural stone, so a pan straight off the burner can leave a mark where the resin softened.
Is granite the safer choice by the window?

Granite is natural stone and handles both sun and heat without changing. It does absorb liquid unless sealed, and the sealer wears off with use around the sink. A basic test is a few drops of water on the surface: if they darken the stone after a few minutes, it is due for another coat. Houses along the Santa Ana River corridor pick up more dust and grit on the surface, which wears sealer faster.
How does butcher block behave?
Wood moves with moisture and temperature. Riverside air is dry, so a block counter loses moisture in summer and can open small gaps at the joints. Oil treatments keep the grain from drying out, and a sunny window dries the surface faster than a shaded wall. It is a warm material that asks for regular care.
What about hot pans and cutting?
Granite takes a hot pan. Quartz wants a trivet. Butcher block scorches and can be sanded back. Any counter takes a knife badly except wood, and a cutting board saves all three. A kitchen near the Box Springs Mountains with afternoon sun straight through the glass should have a sample held in that light before anything is ordered.
Where should the sample go?
On the actual windowsill for a full afternoon. Color shifts under direct sun in the Inland Empire, and a slab that looked warm in a showroom can read flat or glaring in the kitchen it was meant for. A kitchen on the Mount Rubidoux side of town with a south or west window gets the full hours of light, and the counter nearest to it takes the most wear over the years.