> perfectly clear days in the Pacific Northwest, the lack of smog and lower humidity can result in very direct radiation that feels every bit as "stinging" as the desert sun. I'm pretty sure this is my main problem Seattle is just too clean. Absolutely nothing to filter the sunshine. And no breeze to keep you cool (except on the water)

80° sun angle. Higher than 0 to 14°N sun. Sun angle is one factor but not the only one.

The sun is much stronger in San Diego than Seattle in June.

At Seattle's latitude summer solstice sun angle is ~66°. sin(66°) = 0.913 = 91.3% Seattle's summer sunlight is 91.3% as powerful as 90° sun somewhere in the tropic of cancer and identical to the equator. The real difference in sun brightness is in winter, summer sun is barely different from 0 to 55°N.

Summer sun isn't that different between different latitudes. During June solstice Seattle and somewhere on the equator will have similar sun angles