The climate in Iran

Climate zone: Subtropics of the northern hemisphere

For 7 months, the average temperatures are over 25 degrees. Pleasant water temperatures of up to 32 degrees even invite you to bathe in the warm season. The warmest and at the same time rainiest region is Khuzestan. The coldest is Tabriz. Due to the warmer temperatures, the best time for traveling is from June to August. Less attractive are the cold months from November to March.

Temperature records of the last 67 years

The hottest temperature measured from 1956 to January 2023 was reported by the Abadan weather station. In August 2022, the record temperature of 53.0 °C was reported here. The hottest summer from July to September, based on all 38 weather stations in Iran below 1,740 meters altitude, was recorded in 1961 with an average temperature of 31.1 °C. This average temperature will normally be measured every four to six hours, thus also including the nights. Normally, this value is 27.8 degrees Celsius.

The coldest day in these 67 years was reported by the Sanandaj weather station. Here the temperature dropped to -24.5 °C in January 2022. Sanandaj lies at an altitude of 1,373 meters above sea level. The coldest winter (January to March) was in 1993 with an average temperature of 4.3 °C. In Iran, it is usual to have about 4.0 degrees more at 8.3 °C for this three-month period.

The most precipitation fell in December 2005. With 39.9 mm per day, the Ilam weather station recorded the highest monthly average of the last 67 years. Incidentally, the region with the most rainfall for the whole year is around Bandar Anzali. The driest region is near Yazd.

Long-term development of temperatures from 2001 - 2022

In contrast to single record values, long-term development cannot simply be brought about by all weather stations in the country. Both the number and the locations are constantly changing. An average value would give a distorted result. If several measuring stations in particularly cold mountain or coastal regions are added in one year, the average would decrease as a result of this alone. If a station fails during the summer or winter months, it does not provide any values and distorts the average again. The subsequent long-term development was therefore reduced to only 3 measuring points in order to have comparable data over as long a period as possible.

In the years 2001 to 2022, there were only these 3 weather stations in the whole country, which reported continuous temperature values (Tehran, Tabriz, Shiraz). From these weather reports, we have created a long-term development that shows the monthly average temperatures. The hottest month in this entire period was July 2018 at 32.0 °C. January 2008 was the coldest month with an average temperature of -1.2 °C.

The average annual temperature was about 17.3 °C in the years after 2001 and about 17.4 °C in the last years before 2022. So it has hardly changed at all in the past 22 years. This trend only applies to the selected 3 weather stations in Iran. A considerably more comprehensive evaluation of global warming has been provided separately.

Data basis and methodology

The data from the individual measuring stations are based on the archives of the German Weather Service, individual values averaged and supplemented by own elements. In order to determine a representative national average, average values were first calculated for each part of the country, which were then summarized at the national level. Thus, if a disproportionate number of weather stations are located in a small area, their number does not affect the national average. There are 39 stations in Iran itself. In 22 cases, neighboring but nearby weather stations were also used to obtain more accurate values.