Period of odd darkness and silence around middle of day

My brother and his wife, in early July were sitting in their home (most likely on a Saturday as they drive down from their winter home in Sudbury, MA to their vacation house in the wee hours of Saturdays and usually leave early on Sunday, unless they do an extended stay). My brother was downstairs on the couch abutting the northern side of the home, while his wife was upstairs. Suddenly the house went dark (as if a thunderstorm was rolling through - their words). At the same time all sound disappeared, which they described as very peculiar. It lasted for only a brief time. They both ran to the windows (sliding glass door downstairs facing south, and north or south facing windows upstairs). They told me the sky was completely clear with no storms in sight, which baffled them. The date is a guess. They told me it was early July. I deduced Saturday based on their habit of visiting their summer home on the weekends, as mentioned. I refrained from posting this event until new reports that covered July had come in, as I was curious if anyone else had a similar experience in their area in the same time frame. I then saw the retired law officer's report that was also in North Falmouth. Please do not post the name of the street they live on in N. Falmouth for privacy