NASA scientists found the Moon's 18.6-year wobble will amplify ordinary high tides on U.S. coastlines starting in the mid-2030s — meaning some streets could start flooding on calm, sunny days for no v

Key Points:

• A 2021 NASA-led study warns that by the middle of the next decade, a natural 18.6-year lunar cycle will amplify tides, causing significantly more high-tide flooding along U.S. coastlines, compounded by ongoing sea level rise.
• The moon’s orbit tilt cycle, which modulates tidal bulges, will enter its amplifying phase, resulting in higher tides that, combined with elevated baseline sea levels, will cause flooding in areas previously unaffected by ordinary tides.
• NASA projects a three to fourfold increase in high-tide flood days annually for most U.S. coastal areas, with floods clustering in certain months, leading to persistent, minor flooding that cumulatively damages infrastructure over time.
• Unlike storm-driven floods that come with warnings, this lunar-driven flooding occurs under calm conditions without advance notice, making it a slow, often overlooked threat that gradually stresses coastal communities and infrastructure.
• NOAA experts emphasize the need for proactive planning to adapt to this increase in nuisance flooding, which varies by local geography and may require tailored solutions rather than a one-size-fits-all approach.