Even given the changeable weather, I'm surprised at the temperatures
as much as 5 degrees below the July norm for the south of England over
the weekend on the Met Office site. The airmass doesn't seem to be
coming from a notably cold direction and it seems a setup which would
produce showers rather than persistent rain - so to be honest I'd have
expected average temperatures for the time of year (the July average
1961-90 was 22C, for more recent years nearer 23C). On a more general
note there has been a tendency for spells of far-below-average (around
5C) at this time of year since 2004 - if only such spells could come
in winter where they belong!

Nick