After nearly 2 feet of rain fell in central Texas on July 4, causing flooding that killed more than 100 people, almost a foot of rain struck central North Carolina as Tropical Storm Chantal moved inland on July 7.

Both are considered to be at least “1,000-year flood” events. But what does that mean, and how could we see so many events in such a short time period?

1,000-year floods, defined for insurance purposes

Insurance companies use decades-old flood statistics that are based on how often the nearest USGS river gauge (there are about 7,500 nationwide) would exceed a certain amount of water flowing past it.

A 100-year flood means that there is a 1% chance of that flood happening in any given year at your home’s location.

A 1,000-year flood would be a 0.1% chance, so in 1,000 years, you’d expect 1 such flood to occur.

But statistics don’t dictate when during that period the floods will occur, and the floods could happen in rapid succession without violating the rule.

Is my home susceptible to any 100- or 1,000-year floods?

Here’s how to check. Use FEMA’s Flood Map Service Center to check the flood zone classification of your property.

Here’s how:

1. Website: Go to theFEMA Flood Map Service Center
2. Location: Enter your address
3. Review the map: The tool will display a map showing your property and its flood zone classification.
4. Understand the classifications: FEMA flood maps indicate zones with varying flood risks. Zone AE, for example, indicates a higher risk of flooding, with a 1% annual chance of flooding (also known as a 100-year flood zone).