ld waves in the Northern area of Sadi Arabia during 1985-2017

This research provides an analysis of the maximum and minimum temperatures for the period 1985-2017 in Turayf, Gurayat, Al Jawf, Rafha, Tabuk and Ar’ar stations in the northern region of the Kingdom of Saudi Arabia to determine the general trend of heat and cold waves and their indication of a possible climate change during the studied period.
This study seeks to analyze the statistical characteristics of the maximum and minimum temperatures distribution the characteristics of the distribution of heat and cold waves to determine the general trend during the period 1985-2017 and their relationship with potential climate change in the northern region of the Kingdom of Saudi Arabia.
The methodology of this study deals with analyzing the statistical properties of the maximum and minimum temperatures distribution by applying dispersion measures (mean, standard deviation, standard error of the mean, standard error of standard deviation) and analyzing the distribution of heat and cold waves using the Kolmogorov-Smirnov test and the Levene test. Their general trends is determined by applying the Ratio method and the Semi-averages method, with testing its statistical significance by “t” student during the studied period.
This study relied on daily data for the maximum and minimum temperatures recorded during the period from January 1985 to December 2017 at the stations of Turayf (40356), Gurayat (40360), Al-Jawf (40361), Rafha (40362), Tabuk (40375) and Ar’ar (40357) of the General Presidency of Meteorology and Protection The environment. These stations are included in the stations of the National Climate Data Center (NCDC) and is supervised by the World Meteorological Organization.        
The results of the Normality test (Kolmogorov-Smirnov test) and the Homogeneity test of variance (Levene test) showed that the distribution of the number of days and the number of hot and cold waves follows the normal distribution with homogeneity of its variations at the significance level 0.05 during the different months of the year in each station. Pearson correlation examination also showed that the frequency of hot and cold waves (dependent variable)are significantly related to the hot and cold days (independent variable).
Also, the results of ratio test of the general trend of the hot and cold waves monthly frequency showed no increased or decreased trend during the same month in all stations.
The results of the  “t” student test revealed any statistical significance of the general monthly and yearly distribution of hot and cold waves. The values of the standard error impairment exceeded the difference between the semi-averages of hot and cold waves at the significance level of 0.05 during the period 1985-2017.
This study was able to determine the non-significance of the general trend of heat and cold waves in the northern region of Saudi Arabia. Therefore, it is difficult to attribute the variations between the spatial and temporal distribution of the cold and heat waves to the potential climate change during a period of daily temperatures recorded during the 33 years (1985-2017).