We visited York and London last summer and unfortunately were in London during a really hot week in June. It was truly miserable. I thought I would faint in the Charles Dickens Museum. Thank goodness the hotel had ac and the theaters were air conditioned and we had plenty of great pubs like the Lamb and Flag to enjoy! When we arrived in York a week later it was lovely and cool. This year for my 65th birthday, I would like to be in London for at least 5 days. I want to see the King and I and other shows
We will spend a week in Northumberland. We usually visit the UK in June but this year my husband wants to go the last two weeks in July and the first few days of August. Was the weather last June a fluke? Are we more likely to have hotter weather in July and August? I have looked at weather tables and the difference is about 5 degrees. I come from a desert climate but feel the combo of heat and humidity very much and I am on an academic calendar and these months are my only option this year.
The other option for us would be to spend the 2nd week of our vacation in Scotland which I love, but we so enjoy the London theater. I wasn't planning on visiting this year but I have just suffered the loss of a younger brother and this trip is to offer a salvo to my very bruised soul. I'm having a hard time making this decision and would like advice from Fodor's UK experts. I'm more for June as I'm assuming this is before the high tourist season? If we go to Northumberland first then we can cancel our hotel if there is a heat wave and head somewhere else.
Thanks for any comments that would tip me in one direction or another.

Anymore June is just as popular as July and August. Might be a few less tourists but don’t fool yourself in thinking places won’t be crowded. Weather is impossible to accurately predict. I would’t begin to assume one month to be better than another and neither would I assume it to be cooler in Northumberland than London. Maybe, maybe not. Weather in England is often a fluke. If that uncomfortable in hot weather, book a hotel with air conditioning. Most of the big chains and a few upscale hotels will have it. Wish I could be more helpful but after some 30years of visiting England, that’s the best I can do and feel comfortable with my advice.

June might be lovely or rain or hot or all three. July might be lovely or rain or hot or all three. August might be lovely or rain or hot or all three. See a trend here?

The weather could be anything at any time and completely different two days later. There were a couple of days last July that Inverness was hotter than Rome, but it could just as easily freeze your buns off. Cool and/or wet is more common in summer than heat waves -- but heat waves can happen too. So if you are sensitive to heat, book places with a/c.

If you are sensitive to heat, it would be cleverer to go in spring or autumn than in summer. I rarely travel in summer any more for this reason. April/May or September/October are my preferred travel months.

The weather is like the government, it is always wrong.

There is no way to predict this I'm from the North West and visit London often. All I can say is June is warmer than February and August is 3 months before November...its impossible to chart the weather though!

These days, I find the weather in England to be warmer in May, June and July than in August and September but that is purely subjective. The heat in London can be unpleasant but take advantage of the parks, waterfront and aircon in museums and galleries. Avoid Shakespeare's Globe theatre by Embankment on a very hot day - once I saw 12 people faint!

A hotel with with ac is a must and I must pray that we are lucky and we don't encounter a heat wave! When I retire, which is very soon, we will be able to go at anytime. Thank you.