A "coastal flood watch" means that conditions are favorable for moderate to major coastal flooding, which could seriously threaten lives and property along coastlines. This type of flooding happens when seawater moves inland, not just from heavy rain.

There are several key reasons why "coastal flood watch" is trending, largely tied to climate change and its direct effects:

• Rising Sea Levels: Global sea levels have been rising and are accelerating due, in part, to warming oceans (which cause water to expand) and melting glaciers and ice sheets. This means the ocean's baseline is higher, so even normal high tides can reach further inland than before.
• More Intense and Frequent Storms: Climate change can contribute to more powerful storms like hurricanes and nor'easters. These storms generate "storm surges"—a sudden, abnormal rise in water levels pushed towards the shore by strong winds—which become more dangerous when they ride on top of already elevated sea levels.
• "Sunny Day" or Nuisance Flooding: With higher sea levels, coastal areas are experiencing more frequent flooding even during minor tidal events or clear weather, sometimes called "king tides." This is because the gap between average sea level and land height has shrunk.
• Vulnerable Coastal Populations and Infrastructure: A significant portion of the global population and critical infrastructure is located in coastal areas. As sea levels rise and storms intensify, these communities become increasingly vulnerable to damage and disruption.
• Recent Weather Events: Specific weather systems can trigger these watches. For example, recent coastal low-pressure systems combined with high tides and an onshore push of wind have led to coastal flood warnings in regions like the Mid-Atlantic and Southeast U.S.

In essence, the trend reflects a growing concern and reality that coasts are becoming more susceptible to flooding due to a combination of long-term climate changes and immediate weather patterns.