it could hit 110 in Seattle and 120 in Portland?!
That sounds a few degrees higher than most model forecasts (after adjustment for their biases), but we'll see. The models are in substantial agreement that it will be record-setting heat, regardless of what the exact numbers end up being.
In a typical summer we generally get to the 80s and sometimes low 90s away from the water. Near the water it's always cooler, usually 70s. Having mid 90s along the water is crazy. Having mid 100s along the I-5 corridor is ridiculous.
Is it hot enough for birds to fall out of the sky? I have been reading that extreme heat of this type can cause massive die offs.
No, at least not for that reason. The heat doesn't generally kill birds directly. Rather, the extreme ocean temperatures kill the fish that marine birds prey on, so the birds starve and then their bodies wash ashore.