Can dark window frames get hot enough to affect how they work?

For a dark vinyl frame, the most useful spec is any manufacturer limit tied to color and sun exposure, such as a maximum frame temperature or restrictions on dark finishes for particular orientations. Don’t assume that guidance for white vinyl applies to a dark finish.

For all three materials, read the finish warranty separately from the operating instructions. The warranty tells you what appearance-related problems are excluded; clearance guidance addresses whether the sash can still operate as the frame moves. Those are different questions, and the fine print may treat them differently.

Material changes the comparison, but it doesn’t settle it by itself. Vinyl’s temperature-related expansion can matter for sash fit; fiberglass generally changes dimension less with temperature, while aluminum conducts heat readily. Shade reduces solar heating for any of them. Color-specific limits can differ by product and material, so compare the guidance for the actual frame and exposure - not just “vinyl vs. fiberglass vs. aluminum.”

A frame-temperature limit doesn’t automatically tell you whether the coating or adjacent sealant will tolerate the same heat. For the specific window, check the finish’s temperature limits and the manufacturer’s guidance on sealant compatibility, especially if the sealant contacts the frame. Those details can vary by product, even when two windows use the same frame material.