Delaware — Water Temperature Today and Throughout the Year

Sea Water Temperature Along the Coast

Places with the Warmest Sea Water Today

The Most Popular Seaside Places

Coastal Seas and Oceans

Water Temperature in Lakes and Rivers

Popular Lakes

Popular Rivers

Popular Places

Water Temperature and Swimming Overview

Water Temperature Trends

Delaware, situated along the mid-Atlantic coast of the United States, experiences moderate water temperatures due to its proximity to the Atlantic Ocean and the Delaware Bay. In the summer months, ocean water temperatures along Delaware's coastline, such as in Rehoboth Beach or Dewey Beach, typically range from 70°F to 80°F (21°C to 27°C). These temperatures create comfortable conditions for swimming, sunbathing, and other coastal activities. However, during the cooler months of spring and fall, the water temperature can drop to 50°F to 60°F (10°C to 15°C), which may feel too chilly for swimming, although still manageable for those engaged in boating or fishing. In winter, the temperature can drop further to around 40°F (4°C), making the ocean waters much too cold for recreational use.

The rivers in Delaware, such as the Delaware River and the Nanticoke River, show more variation in temperature, with colder conditions in the winter and warmer waters in the summer. During the spring and early summer, the river temperatures typically range from 50°F to 65°F (10°C to 18°C), especially in the slower-moving sections. In the warmer months of late summer, temperatures in the rivers can rise to 70°F to 80°F (21°C to 27°C), making them more pleasant for activities like kayaking, fishing, or swimming in the less turbulent areas. However, in the colder months, river temperatures often drop to 40°F to 50°F (4°C to 10°C), which can make swimming less inviting.

Delaware's inland lakes and ponds, such as Silver Lake and Trap Pond, tend to have warmer water than the rivers and ocean. During the summer, water temperatures in these lakes can range from 70°F to 80°F (21°C to 27°C), making them ideal for swimming, boating, and other water activities. The relatively shallow nature of many of Delaware's lakes allows them to warm up quickly in the warmer months, offering a refreshing alternative to the cooler ocean and river temperatures. However, as the weather cools in the fall, lake temperatures can drop significantly to 50°F to 60°F (10°C to 15°C), and during the winter, the lakes can experience freezing temperatures, especially in the northern parts of the state.