Short Answer
Roof color can influence solar heat absorption, but attic temperature is also influenced by ventilation, insulation, air sealing, roof assembly, solar exposure, and climate. Roof color alone does not determine attic temperature.
Detailed Explanation
Darker shingles do absorb more solar heat than lighter shingles, which can increase roof surface temperature. But whether that translates to a significantly hotter attic depends on the ventilation, insulation, and air sealing of the attic space. A well-ventilated attic with proper insulation will maintain a temperature close to the outside temperature regardless of shingle color. A poorly ventilated, under-insulated attic will be hot regardless of shingle color. While lighter shingles can provide a slight cooling benefit in hot climates, the impact is generally less significant than the effect of proper ventilation and insulation. Color choice should primarily be based on aesthetics and neighborhood compatibility.
Why It Matters
Choosing shingle color based solely on perceived temperature impact overlooks the more significant factors of ventilation and insulation that actually control attic temperature.