Warm weather with a newborn

We’re visiting our in-laws next week and the weather should be in the 90s all week and even over 100 a few days. They don’t have AC and we have a newborn. She likes to be swaddled at night, but I’m worried about her getting too hot. Any tips to keep her cool and comfortable in a hot environment?

Also, they have a pool, but I wonder if she’s too young for the pool? Any tips for swimming with a newborn?