Climate change has a significant impact on the environment as well as the social, economy. Tigray is one of the sensitive regions to climate variation particularly to rainfall changes. In this study, we analyzed rainfall variability at annual and seasonal time scales, for the periods 1984-2014. Daily observed climate data was collected from the National Meteorological Agency of Ethiopia (NMA). Temporal rainfall variability was assessed through the timing of onset date, end date, length of growing season and dry spell length using INSTAT climate guide. Moreover, long term monthly Eto was calculated using CROPWATH MODEL. The variation was high due to the variability of daily and monthly weather condition over the study area.

The long-term annual rainfall in the study area showed high variability from year to year which was 22.9%. Seasonally, the ONDJF, JJAS and MAM total rainfall also showed high variability which was 89.7%, 24.7% and 62.7% respectively. Except onset date, cessation date and length of growing season were highly variable. The onset date, offset date and length of the rainy season/JJAS were on 184DOY/02JUL, 261DOY/17SEPT and 77 days respectively. Moreover, the minimum dry spell days length converges from 201DOY-241DOY (19July-28Aug) and turn upward again from 241DOY-261DOY (28Aug-17Sep). Thus the maximum Probability of occurrence of dry spell length during the main (JJAS) season implies a negative impact on the agricultural activities of the study area during the study period (1984-2014).