What is the Temperature Inside a Car Trunk at 40°C in Summer?
2 Answers
In summer, when the outdoor temperature reaches 40°C, the temperature inside a car trunk can reach around 50°C. Here are some solutions to address excessive heat inside a vehicle during summer: 1. Park with the rear facing the sun: Choose a shaded parking spot whenever possible. If you must park in direct sunlight, position the rear of the vehicle toward the sun. Since rear windows are smaller, they allow less sunlight penetration, reducing heat accumulation in the cabin compared to parking with the front facing the sun. Ideally, use a car cover or install sunshades on the windshield to block direct sunlight. 2. Water spray cooling: When the interior temperature is high, spray water inside the car (adding some alcohol to the water helps faster evaporation and heat absorption). Open doors and spray several times, then close doors without opening windows - the temperature will drop within minutes. Note: Pure alcohol has a flashpoint of 75°C, with lower concentrations having higher flashpoints. Recommended is 75% medical alcohol diluted with water at 1:10 ratio. 3. Door fanning: Open all doors and repeatedly swing them to manually expel hot air, quickly reducing interior temperature. Be mindful of force and note this method isn't suitable for butterfly or gull-wing doors. 4. Air circulation: First open windows for ventilation. When the vehicle stabilizes, turn on AC with external circulation. When interior and exterior temperatures equalize, close windows and switch to internal circulation - this is the standard cooling procedure.
During summer when temperatures reach 40 degrees Celsius, the temperature inside a car's trunk can skyrocket, a phenomenon I often observe. When parked under direct sunlight, the trunk becomes like a small steamer, as sunlight exposure and heat absorption by metal components inside the car cause rapid internal temperature rise. Typically, with an ambient temperature of 40 degrees, after just one hour of parking, the trunk temperature can easily reach 60-70 degrees Celsius, especially in black cars or when parked on asphalt surfaces. Through my own testing, a thermometer placed inside showed temperatures peaking around 65 degrees—hot enough to burn on contact. This has significant implications: rubber components may harden and age, such as trunk seals that can crack over time, leading to poor closure. Therefore, during hot summer parking, I always recommend choosing shaded areas or using car covers to reduce radiant heat, protecting the interior and extending its lifespan. Prolonged exposure to sunlight also wastes air conditioning efficiency, requiring extended cooling after startup, which can slightly increase actual fuel consumption.
