Climate change research is an important field of study. Because of the refractivity of the earth's atmosphere, Global Positioning System (GPS) signals have a significant delay, making them a suitable approach for studying atmospheric weather phenomena. The zenith wet delays (ZWD) can be determined using GPS measurements. The capability of computing precipitable water vapour (PWV) from GPS signals is helpful to comprehend unique weather events. There are two objective for this work, firstly, zenith tropospheric delay (ZTD) is estimated for total of 20 GPS stations. Results demonstrated that the average root mean square (RMS) and standard deviation (STD) of ZTD estimate is 2440.1 and 63.6 mm, respectively. We compared the calculated ZTD values with the ZTD products offered by Center of Orbit Determination in Europe (CODE) products. Comparison results showed that the average difference and STD between estimates of ZTD and CODE products is 4.84 and 3.77 mm, respectively. Secondly, estimates of ZWD is used to determine the PWV. According to the PWV estimation results, the average RMS and STD value is 35.89 and 11.14 mm, respectively. PWV estimates for 10 IGS sites are compared with Radiosonde (RS) data. Comparison results show that the GPS-PWV estimates and RS data that the R's squared, bias and difference in STD is, respectively, 0.94, -0.24 and 3.99 mm. In addition, the differences of STD between RS-PWV and GPS-PWV is 3.88 and 4.08 mm, at UTC 00:00 and UTC 12:00, respectively.