Over the past few months, one of Pokémon Go's more interesting updates has been the testing around legendary raid lunch hours. One Wednesday per month, usually the first Wednesday, players would have an hour around lunch time where pretty much every gym in the area would feature legendary raids at the same time. It was a fun way to get everyone out and raiding at once, and to crack out multiple attempts at a raid in quick succession.
Apparently, Niantic's testing of this raid hour hasn't yet finished, as they're trying something drastically different in June. Instead of one raid lunch, we're getting weekly raid dinners.
In June, every Wednesday, from 6pm-7pm UK, legendary raids will be popping up with dramatically increased frequency. This is basically just late enough in the day for people to finish work, drop off their belongings, and jump right back out for an hour of walking and battles with their local community.
Considering that Cresselia has been the current legendary raid for quite some time, it's unlikely that these first two weeks will be too busy, but on June 18th Kyogre returns to raids, and will be available as a shiny version in rare instances, which makes the latter half of this month considerably more exciting.