The township of Semnan is confined to the limits of the township of Garmsar from east, to the township of Damqan from west, and to the north are Mazandaran province and the township of Firooz Kooh. The center of the township of Semnan is the city of Semnan which is at a distance of 221 km. from Tehran. This city lies on the route from Tehran to Khorassan province, both on the road and railway network. At the beginning of the 4th century AH., Semnan was the realm of the Al Ziyad dynasty after which the Al Booyeh dynasty ruled. In those periods the cities of Gomess were considered as part of the Daylam territory.
In the year 427 AH., the Turks of Qaz, were liable for vast damages in this vicinity, and in the year 618 AH., the city was raised to shambles during the Mongol invasion. Later on, during the Safavid and Qajar eras, the city thrived once again. Today, it is a flourishing and beautiful city. Past historians have made repeated mention of the said in their records.
The city of Semnan enjoys the traditional four seasons of spring, summer, winter, and autumn each year.
The rain season starts in December and lasts all the way into May, however, precipitation throughout the winter months generally falls in the form of light snow, and the rest of the precipitation throughout the rain season is generally very light to moderate. During some winters, moisture-abundant blizzards make their way down from the Alborz mountains from the north of the city and dump several centimeters of snow in a single twenty-four-hour period. These blizzards force the closure of the airport, schools, small streets, and alleyways. As a result of the city's position in a semi-arid plain, many winter days are dominated by a cold and gusty wind that often produces a potent windchill factor which makes the city feel much colder than the actual air temperature. According to Iranian Meteorology reports, Semnan experiences around 48 days in which the temperature falls below freezing each year.