Yes Spring has been interesting if disappointing with the lack of any real warmth and the models aren't that hopeful to a point either.
Summer could go either way and there have been years heat has come out of nowhere reading information such as 1975 (hot July and August), 1983 (one of the hottest July's ever and a top 10 August), 1991, 2013 (July and even August to a point) and of course 2018 (even though May was hot) and 2019 (late June onwards).
It does risk being a disaster and whilst 2011 had a warm spring (I remember April being warm), the summer was a flop save a few warm days. You also had 2007 (had a hot April and the Rhianna summer), 2008 (warm days in May and June was decent but rest vile) and 2012 (horror show but a hot end to May). There's also the cool ones of 1985 and 1986...the latter holds one of the coldest August's ever.
Personally I am verging into the summer being a pile of pants camp. It's been a good nine years since a woeful summer and I think 2021 may be the one. I'll probably be wrong but let's see.....