Dissertation (MSc Telecommunication)Free Space Optics communications (FSO) has drawn a bunch of attention for a range of applications in telecommunications field. The unregulated bandwidth which is up to 200THz, security, higher speed, unlimited data rate, low deployment cost, and shortest installation time frame are the few reasons to employ FSO system. However, weather attenuation has a massive impact on the FSO transmission channel. In this study, the effect of scintillation on the performance and FSO link availability evaluation is analyzed in terms of eye diagrams, Bit Error Rate (BER) and Q-factor, the examination of signal to noise ratio (SNR) was also considered. Two prediction models Submarine Laser Communication (SLC) II and Hufnagel Valley (HV) day were compared to attain the finest prediction model performance for selected data regarding particular meteorological conditions of Mwanza and Arusha regions. HV day model had the best performance for predicting scintillation intensity for the scintillation data taken from January 2015 to December 2018 which totals up to a 48 months period. The simulation shows, the FSO transmission for below 6km distance produce the better quality signal than transmission for 8km and above distance where at 8km distance, the BER value is 10-7 which produce the bad quality signals at receiver for both two regions. However, the FSO link availability decreases with increase in transmission path, FSO link is feasible in both Arusha and Mwanza regions for about 6km range and therefore is recommended for adoption for both regions.