ROCHESTER, N.Y. – We are just a week into May, and already one of the most useful weather instruments is proving its worth. It is the classic rain gauge. This simple tool, often made of clear plastic, helps measure liquid precipitation right at your home or workplace. And it is important because rainfall is cumulative—it adds up over time.

That is especially relevant in Western New York, where rainfall totals can vary significantly even across short distances. Over the last five days alone, different areas have measured variations of one to two inches or more. These differences can have an impact on gardening, landscaping, and even local water management.

If you do not already have a rain gauge, you can make one at home with just a few supplies. Here is a fun and educational way to build your own device.

Start with an empty, clear plastic two-liter bottle. Carefully cut off the top portion of the bottle (and if you’re young, ask a parent or adult for help). Turn that top piece upside down and place it back inside the bottom half, creating a funnel. Secure the two pieces with tape. Next, use a ruler and a strip of masking tape to mark measurements from zero to five inches in one-inch increments. Attach the tape to the side of the bottle so you can track your rainfall accurately.

Just like that, you’ve built a working rain gauge! It is a great way to be a backyard meteorologist and get hands-on experience measuring the weather!