Our ISP is upgrading the operating system on our server Thursday morning.
Hopefully, the site will be down for only a few minutes (the ISP says "less than ten"), as the new OS is installed and the machine is rebooted. Our machine is scheduled to be rebooted sometime between 4:15 and 5:30 AM Pacific Time.
I plan to be sleeping during those hours, so if, for some reason, the system fails to come up automatically after the reboot, the downtime might last a little longer, until I decide to drag my weary tail out of bed.
The old body doesn't take to waking up at strange hours anymore. I need my beauty sleep. You'll live.