You can currently set alert blackouts, but the only way I know of at an aggregate scale would be to update COND directly with a scheduled script.
If you look at the COND table in your repo, you'll see a couple columns - command and status. You can update the command to 'STOP' or 'START' as you desire which will turn off and on monitoring respectively. Status will show what the current state of monitoring is.
Not totally sure why you'd do this unless you just don't want to get notifications - in that case, you can setup alerting blackouts as mentioned in the alert functionality.