A few weeks ago, Delta announced that it would be reducing about 100 flights a day between July 1 and August 7. In the email to its employees, the airline noted that these preemptive cancellations will be used to “build additional resilience in our system and improve operational reliability for our customers and employees… relieve pressure by proactively thinning the schedule.”
Airline Travel: Midsummer Nightmare
Also, flying earlier in the day is more preferable to later in the day since your plane and crew are subject to fewer upstream dependencies.