Ae extratropical cyclone” is an at- mospheric phenomenon that occurs when there is a very rapid drop in central atmospheric pressure. This phenomenon, with its characteristic of rapidly lowering the pressure in its interior, generates very intense winds and for this reason it is called explosive cyclone, “cyclone bomb” CB. It was determined the mathematical equation of the shape of the extratropical cyclone, being in the shape of a spiral called "Cotes’s Spiral." In the case of CB, which formed in the south of the Atlantic Ocean, and passed through the south coast of Brazil in July 2020, causing great damages in several cities in the State of Santa Catarina, Southern Brazil. With gusts recorded of 116 km/h, atmospheric phenomenon – CB hit southern Brazil on June 30, the beginning of winter 2020, causing destruction in its influence over. In five hours the CB traveled a distance of 257.48 km (159.99 miles), at an average speed of 51.496 km/h (31.998 miles/h) 27.81 knots, moved towards ENE, with a low pressure center of 986 mbar, 07:20 UTC, approximate location 35◦S 45◦W, and 5 hours after 12:20 UTC had already grown and had a low pressure center of 972 mbar, approximate location 34◦S 42◦30’W. The temperatures of the clouds and the surface near the low pressure center of the CB. The temperature in the center of the CB is approximately 45◦C at 07:20 UTC, July 1, 2020. Five hours later, at 12:20 UTC, in the low pressure center of the CB, the temperature varies from 45◦C to -30◦C, indicating that the CB increases in size and further tapers its core, sucking a great amount of steam to high altitudes of water where it condenses quickly.