High-pressure systems cause water levels to lower out in the ocean, leading to sunny weather and lower-than-usual tides. Low-pressure systems cause water levels to rise, leading to cloudy, rainy days with higher-than-usual tides. Each inch of mercury drop in atmospheric pressure results roughly in a 13-inch rise in the water level.
Onshore winds force water to accumulate on the shoreline, causing a higher water level during low tide. Offshore winds carry water away from the coastline, exaggerating the low tide.
Extended amounts of rainfall can overflow into rivers that then dump into the ocean. Water piles up where the rainfall and ocean meet, leading to higher water levels.
Strong waves accompany powerful winds in the open ocean. The waves have considerable effects near the shore. This extra momentum can cause water to reach far up on the beach, especially during high tide.