I have been baking sourdough for a number of years mostly very successfully. In recent weeks during the hot weather I have had some disasters. I prove the dough overnight and that rises as normal but then I shape it the next morning to bake in the afternoon and this second rise has typically been very poor.. Sometimes if I turn it out to bake it collapses and I have a very flat loaf, other times it remains round but with very little rise. The last loaf turned out better on a cooler day today's is small again with higher temperatures. Any suggestions?