The American School Counselor Association has some great ideas for talking with children about hurricanes and flooding. Check these resources out at their website. 

In addition, here are some additional resources:

Helping Children after Natural Disasters:  Colorín Colorado is a bilingual site for educators and families of English Language Learners based in Washington, D.C. that has specific, updated resources posted to offer guidance to families and schools related to natural disasters and some posted specific to Hurricane Harvey listed under Featured Resources. You are welcome to print copies of their materials for personal use or educational purposes as long as credit is given to Colorín Colorado and the author(s). Permission to publish materials must be granted by the copyright holder.  Because they get their articles from a variety of sources, please check the bottom of each article for special reprint permissions or additional restrictions from the publisher.

Link:  http://www.colorincolorado.org/article/helping-children-after-natural-disaster

Coping with National Disasters:  This website features free lesson sharing funded by the American Federation of Teachers. Built by educators across the country, it brings together a community of teachers, paraprofessionals, school related personnel, parents, and partners to provide resources.  The devastation and loss of life from events such as hurricanes or a tornado can be emotionally damaging to children. These resources will help you and your students understand and cope with natural disasters. The lesson plans are grouped by topic, subject and grade level and include resources from a variety of agencies.

Note:  You must sign-up for a free membership to access these lesson plans.  They are NOT screened and are contributed by authors under creative commons from across the United States.

Link:  https://sharemylesson.com/collections/coping-natural-disasters

Helping Kids Cope with National Disasters:  This is a website from the National Wildlife Federation (NWF) based out of Virginia.  They provide resources for educators about all subjects connected to the environment; they have a section focusing on how to help kids cope with national disasters.

Link: http://www.nwf.org/Eco-Schools-USA/Become-an-Eco-School/Hurricane-Sandy/Helping-Kids-Cope.aspx