On the morning of August 14, 2021, the Perseid meteor shower displayed an unexpected outburst of meteors between 06:00 and 09:00 Universal Time (1:00-4:00am CDT). So far we have received visual confirmation of an impressive display of Perseids from observers in Wyoming and Ontario, Canada. AllSky camera systems located in Iowa have recorded between 900-1100 meteors each during the course of the entire night. My AllSky system, located outside of San Diego, CA, recorded just under 600 meteors with cloud interference and a lower radiant altitude. The cause of this outburst is currently unknown but is probably the result of an unknown filament of comet debris produced by comet 109P/Swift–Tuttle as it raced through the inner solar system many centuries ago . Rates are normally 50 percent lower each preceding night after maximum but these rates are two to three times more than was seen during the expected maximum on the night of August 12/13. More information will be provided as it arrives…
References: https://www.meteornews.net/2021/08/14/strong-outburst-perseids-on-august-14-2021-06-09-ut/
Heather M. Wendelboe: Personal Communication
Michael Hankey: Personal Communication