Hi, I had read that Airbnb has now added the Caldor fire to extenuating circumstances (allowing full refunds), at least in California. And if an area is either under an evacuation zone or warning area, I cant imagine you would not be able to get a refund. I'd advise reaching out to the host first and see if they would consider rescheduling your stay. As a host, I have a personal policy that if conditions can't ensure a guest is going to get the experience advertised when they booked, I offer a 100% refund, or reschedule, as the guest prefers. I think there are many hosts out there that operate in a similar manner; it just feels like the right thing to do. You go to Tahoe to recreate outdoors, not sit inside a house in the middle of an unfolding natural disaster. I'm so sorry, and can't imagine there aren't many others in exactly the position you are in. I think guests need to speak up, contact airbnb; I feel there need to be policy changes to protect guests from losing deposits (which can be substantial in high demand vacation areas) when the cancellation isn't because of a personal choice, but rather an extreme environmental condition that could compromise their health during a stay. If a refund is hard for a host, then at the very least a credit for a future stay should be given.
Am so sorry you are experiencing this, I hope it gets resolved!