Metoffice/BBC is showing Hail on Wednesday in Surrey area. Is Wednesday going to be a bad weather day or are things vary variable at the moment? Maybe it will change and the sun will come out, it is nearly August.
Things like hail are really hard to predict for any one area. The weather is very variable at the moment, dominated by the atlantic rather than high pressure but unless you have a fairly predictable weather front or deep low pressure then any forecast is likely to be pretty messy at present.