I keep a supply of waterproof paper around at track events for use in a laser printer, when the weather call for rain. It beats reading the soggy and torn paper that officials turn in with their results.
While measuring, I use the smaller, all weather, pocket sized notebooks that are printed with a grid on one side. I use the grid for sketching diagrams. The notebooks are inexpensive, bright yellow and may be used for anytime.
There are a several companies that manufacture waterproof paper. You can find the Rite in the Rain products online at Amazon, Walmart, eBay, and other locations.