Climate change is a worldwide issue which has a dramatic influence on temperature, precipitation, glaciers, and water bodies. The climate of the Earth is getting warmer significantly. This, in turn, increases such extreme weather events as heat and cold waves. To understand these two extreme weather events, the data on the mean daily minimum and maximum temperatures were collected from 39 meteorological stations over the period 1966–2018. These stations were selected because of their long-term data records, the lack of statistical deficiencies, and their proper spatial distribution throughout the country. The aim of this study was to investigate the frequency and spatio-temporal changes of heat and cold waves. After forming the time series for heat and cold waves by employing the Baldi approach, and using the non-parametric Mann-Kendall test and Sen’s slope estimator, their spatio-temporal variations were investigated. The results showed that the mean daily minimum and maximum temperatures were higher in the recent years and decades. Compared to the data recorded in the 1970s, the maximum temperature increased by about 1.5°C, and the minimum temperature rose by about 1.9°C in the recent years (2011–2018). As a result, the frequencies of heat waves (cold waves) have increased (decreased). In this regard, about 85% of the selected stations showed increases (decreases) in the frequencies of heat waves (cold waves). The station in Yazd exhibited the largest trend in increasing (decreasing) frequencies in heat waves (cold waves) at the 99% significance level.

气候变化是一个全球性问题，对温度，降水，冰川和水体产生巨大影响。地球的气候正在显着变暖。反过来，这又增加了诸如热浪和冷浪之类的极端天气事件。为了了解这两个极端天气事件，收集了1966-2018年期间39个气象站的平均每日最低和最高温度数据。选择这些站点的原因是它们的长期数据记录，缺乏​​统计缺陷以及它们在全国范围内的适当空间分布。这项研究的目的是调查热浪和冷浪的频率和时空变化。在采用Baldi方法形成了热浪和冷浪的时间序列之后，并使用非参数Mann-Kendall检验和Sen斜率估计量，研究了它们的时空变化。结果表明，近年来和数十年来，平均每日最低和最高温度更高。与1970年代记录的数据相比，近年来（2011-2018年）的最高温度升高了约1.5°C，最低温度升高了约1.9°C。结果，热波（冷波）的频率增加了（减少了）。在这方面，大约85％的选定电台显示热浪（冷浪）的频率增加（减少）。亚兹德的台站在热波（冷波）中以99％的显着性水平呈现出增加（减少）频率的最大趋势。结果表明，近年来和数十年来，平均每日最低和最高温度更高。与1970年代记录的数据相比，近年来（2011-2018年）的最高温度升高了约1.5°C，最低温度升高了约1.9°C。结果，热波（冷波）的频率增加了（减少了）。在这方面，大约85％的选定电台显示热浪（冷浪）的频率增加（减少）。亚兹德的台站在热波（冷波）中以99％的显着性水平呈现出增加（减少）频率的最大趋势。结果表明，近年来和数十年来，平均每日最低和最高温度更高。与1970年代记录的数据相比，近年来（2011-2018年）的最高温度升高了约1.5°C，最低温度升高了约1.9°C。结果，热波（冷波）的频率增加了（减少了）。在这方面，大约85％的选定电台显示热浪（冷浪）的频率增加（减少）。亚兹德的台站在热波（冷波）中以99％的显着性水平呈现出增加（减少）频率的最大趋势。最近几年（2011-2018年）的最低温度上升了约1.9°C。结果，热波（冷波）的频率增加了（减少了）。在这方面，大约85％的选定电台显示热浪（冷浪）的频率增加（减少）。亚兹德的台站在热波（冷波）中以99％的显着性水平呈现出增加（减少）频率的最大趋势。最近几年（2011-2018年）的最低温度上升了约1.9°C。结果，热波（冷波）的频率增加了（减少了）。在这方面，大约85％的选定电台显示热浪（冷浪）的频率增加（减少）。亚兹德的台站在热波（冷波）中以99％的显着性水平呈现出增加（减少）频率的最大趋势。