In traditional concepts, heatstroke is a seasonal disease unique to the dog days. However, reality is not always the case. Based on the emergency treatment situation at Renji Hospital, there was no peak incidence of heatstroke under extreme high temperatures. The reason is simple. After knowing the weather forecast for extreme high temperatures, both individuals and units will strengthen heatstroke prevention and cooling measures, thereby reducing the chances of heatstroke. According to clinical observations, the peak of heatstroke mostly occurs in muggy weather with temperatures ranging from 30 ℃ to 35 ℃ (even less than 30 ℃). As is well known, heat transfer involves conduction, radiation, convection, and evaporation. Air is a poor conductor of heat, and heat conduction and dissipation are basically ineffective; When the temperature exceeds the body surface temperature, the thermal radiation from the human body to the environment basically stops; When the environment is calm, convection can be almost negligible; Evaporation, as the main heat dissipation force of the human body, basically stops when the relative humidity is greater than 75%. And Huangmei Tian precisely meets the three factors that cause heatstroke: "high temperature," "no wind," and "high humidity. Let's take a look at two typical cases: Ms. Xiao, 32 years old. One day in late May, the weather was stuffy and the temperature was 30 ℃. After going out for a long afternoon, she began to experience nausea, mild diarrhea, fatigue, and dizziness in the afternoon. After returning home, turn on the air conditioning, take a shower, drink water, and relieve symptoms at night. Mr. Fan, 24 years old, one day in June, with a temperature of 33 ℃, went to a water park to play and was exposed to the sun for a day. He experienced chills and trembling while taking a bath in the bathtub, followed by a fever with a temperature of 39 ℃, accompanied by nausea and diarrhea. The symptoms relieved on the third day. Most people have experienced similar 'heatstroke', but the symptoms are not specific enough, ranging from mild to moderate, mostly due to dizziness, nausea, mild diarrhea, fatigue, fever, etc. after being exposed to hot weather. In order to prevent serious heatstroke events, everyone should remember the precautions to prevent heatstroke: 1. Most heatstroke cases are mild to moderate, and early identification of discomfort, getting out of a stuffy environment, supplementing water and electrolytes, and most symptoms can be quickly relieved. 2. In hot and humid weather, do not engage in aerobic exercise outdoors naked. 3. It is sometimes difficult to distinguish heatstroke and other diseases, and it is not recommended to make a self judgment. It is important to seek medical attention in a timely manner to avoid delaying treatment opportunities. 4. For people with underlying diseases, infants, and the elderly, avoid exposure to high temperature and humidity environments. Do not hesitate to use air conditioning for cooling. Once heatstroke occurs, the difficulty of treatment will significantly increase. Feng Nan (Emergency Department of Renji Hospital affiliated to Renji Hospital)