The Big Butterfly Count this year started on 14 July and runs to 6 August, so you’ve got a few days to join in.
Given some reasonable weather, you stand a good chance of seeing some butterflies. This graph from our ‘This year v last year’ page shows how much better butterflies are doing this year (the darker the blue, the more the sightings received):
Full information can be found on the Big Butterfly Count website.
It only takes 15 minutes – and what a great excuse to sit and watch butterflies!