Why is Delaware, USA, so hot? Causes and how to cope with the heat.

Delaware on the U.S. East Coast is a small state but tends to experience hot and humid summers. The climate characteristics differ slightly between the coastal and inland areas. Here, we explain in detail the reasons why Delaware gets hot, how to deal with the heat, and some cool spots.

1. Reasons Why Delaware Gets Hot

1-1. Humid Coastal Climate

• Delaware has a humid Atlantic climate, where summer temperatures are around 30°C (86°F), but the humidity is very high, making the apparent temperature sometimes reach 35–40°C (95–104°F).
• High humidity prevents sweat from evaporating easily, causing heat to linger in the body.

1-2. Moist Air from the Atlantic Ocean

• The southeastern part faces the Atlantic Ocean; sea breezes sometimes bring coolness but also increase humidity.
• Tropical storms and the Gulf Stream influence the area, allowing hot, humid air to flow in during midsummer.

1-3. Heat Retention in Inland Areas

• Inland areas such as Dover and Newark experience weaker sea breeze effects, causing heat to accumulate during the day and temperatures to remain high at night.
• Urban areas have asphalt and concrete that store heat, causing a heat island effect.

1-4. Thunderstorms and High Humidity Cycle

• Summer afternoons often have thunderstorms or showers, temporarily lowering the temperature but followed by a quick rise in humidity again.

2. Heat Countermeasures

2-1. Personal Measures

• Frequently hydrate and replenish salt, and shift outdoor activities to morning or evening.
• Wear breathable clothes, hats, and sunscreen.
• Use cooling towels and portable fans.

2-2. At Home

• Use blackout curtains or bamboo blinds to block sunlight.
• Use a dehumidifier along with air conditioning to reduce humidity and improve comfort.
• Plant greenery near windows or outdoors to create natural shade, known as “green curtains.”

2-3. Community-Level Efforts

• Delaware opens Cooling Centers during summer for public use.
• Programs providing air conditioning subsidies for the elderly and low-income residents are also implemented.

3. Cool Spots (Places to Escape the Heat)

3-1. Coastal Beaches

• Lewes and Rehoboth Beach have sea breezes, making the apparent temperature lower than inland areas.
• However, humidity remains high, so staying in the shade or near water is effective.

3-2. Riverside and State Parks

• Brandywine Creek State Park and White Clay Creek State Park offer cooling effects from forests and rivers.

3-3. Northern Hill Areas

• The hilly areas near the Pennsylvania border are somewhat elevated, making them a few degrees cooler than the flatlands.

Summary