Like this and this (for Australia), and this (for USA). The second is designed to use any old IR remote you may have lying around.
Many hardware store chains have them these days.
However, RF RC devices are not always sure to work if there are a lot of RF obstacles around, like walls and metal frames.
I also don’t know if I would rely on them in electrical storms. For those wanting guaranteed shutdown in such storms, going to the main power board and flicking off the main switches for the required lines, or even the master (fridges will keep things cool for a few hours), is going to protect the best, and keep the hidden house wiring from getting fried.