Used to live in Hong Kong, so had been in Thailand for over 20 times any month of the year, because of affordability, food, hospitality, culture and water sports.
Is it hot? Yes, very hot, especially in the summer months. I would avoid Bangkok in July. Go to the north, e.g. Chang Mai or Chang Rai, where the mountain provides a cooler weather, only in a relative sense. Or, go south to Phuket. It is still humid and hot, but the beaches provide excellent opportunity to cool off.
Is there any flood? It is a game of probability. Summer is the rainy season in the north. The whole country has tropical rainstorm almost daily just like Orlando. Rain is manageable in Thailand. It won't affect you itinerary much.
The best travel season is November to April. The worst is September and October when the whole country is unbearably humid and hot. July is like in-between.
Would I go in July? No. Why? Because the cheapest airfare probably is via Hong Kong, and if you want to stop over there for a few days, Hong Kong is too hot for any comfort travel. The temperature in the past few days was like 38C.