Hashem was making it rain during shacharis. I thought that I might hear thunder between ahavah rabah and shema. I know that we don’t answer amen to other brachos at that point, would I be allowed to make a bracha on the thunder ?
Between Ahava Rabba and shema is considered between perakim. It is permitted to say the bracha on the thunder between perakim, if you are afraid that there won’t be another thunder when you finish davening. The reason being that since it is a mitzva that will not present itself after davening it is permitted between perakim. In middle of a perek it is controversial and therefore it is better not to say the blessing on the thunder at that point.
M:B 64-19, Bais Baruch on Chayei Adom 20-28, Eishei Yisroel 19-10.