This study examined the extent of seasonal rainfall variability, drought occurrence and the efficacy of interpolation techniques in the drier regions of eastern Kenyan. Rainfall Anomaly Index (RAI) and Coefficients-of-Variance and probability were utilized in the analyses of rainfall variability. Analyses showed 90% chance of below cropping-threshold rainfall (500 mm) exceeding 258.1 mm during short rains (SRs) in Embu for one year return-period. Rainfall variability was found to be high in seasonal amounts (eg CV= 0.56, 0.47, 0.59) and in number of rainy-days (eg CV= 0.88, 0.49, 0.53) in Machang’a, Kiritiri and Kindaruma respectively. Monthly rainfall variability was found to be equally high during April and November (eg CV= 0.48, 0.49 and 0.76) with high probabilities (0.67) of droughts exceeding 15 days in Machang’a and Kindaruma. Dry-spell probabilities within growing months were high eg 91%, 93%, 81% and 60% in Kiambere, Kindaruma, Machang’a and Embu respectively.