It's so dry in London now, that we are forced to get to the allotment twice a week, in order to water everything. Some summers we don't even get the hose out! But I think since Easter, we have watered nearly every week, and some plants are wilting really, as watering is not really adequate. Also, many are going to seed, which I think results from dry weather - I sowed some chard a few weeks ago, and it has grown and gone to seed already. Quite bizarre.
If you believe in rain dancing, now is the time, folks.