Dear Mr./Ms. Bossname,
Unfortunately, I must resign from XYZ Company. As you know, I lost my home in the recent natural disaster. Rather than rebuild, my family has decided to move out-of-state.
I appreciate the opportunity to have worked with XYZ and hope than you can provide a good reference for me in the future. I anticipate that it will take us two or three months to get established, at which point I will be looking for work similar to what I did here.
Thank you for your support and patience as my family deals with evacuation and cleanup.