Canary Islands is always my go to warm and nice in any time of the year
Most places are warm enough for a 2 year old by then… any of the Balearics are great from families. We stayed in Bitacora hotel in Tenerife last May & great for kids… just try and avoid the half term price hike!
I went to Greece mid May and was lovely weather, I think 28-30 however if you like to swim in the sea it was freezing and apparently September is best ,
We went to Turkey end of May last year with our then 7 month old and stayed at the Paloma Orenda which was fab for kids and adults x