We present the latitudinal variation of ionospheric phase scintillation over east African sector during geomagnetic storm of the year 2015 using VTEC rapid fluctuation, ROT fluctuation and ROTI enhancement. The rate of change of TEC (ROT) and the rate of change of TEC index (ROTI) that can be obtained from widely dispersed IGS stations performing two frequency GPS satellite observations can be used, as especially in the equatorial region, as an indicator of the presence of scintillation causing small-scale ionospherical irregularities. In this study, we use ROTI to investigate the presence of scintillation and how this scintillation varies with latitude over east Africa during March 17, June 23 and December 20, 2015 geomagnetic storms. We selected chain of seven ground-based GPS receivers with stations codes and geomagnetic coordinates: ABOO (8.99N, 37.8E), ARMI (6.06N, 37.53E), BDMT (11.6N,37.35E), ASAB (13.06N, 42.65E), DODM (-6.18S, 35.74E), MAL2(-2.99N, 40.19E) and MOIU (0.28N, 35.29E). We analyzed by taking ROTI mean with latitude, on march 16 and 17, we observed that maximum ROTI mean value at DODM (Tanzania) low latitude, so, we conclude that maximum phase scintillation was observed here during march 17 storm. During June 23 and December 20 geomagnetic storms, maximum ROTI mean value was observed at MOIU (Kenya) equator, so, we concluded that high phase scintillation was observed at MOIU during these storms. So, as we go from high latitude to magnetic equator the occurrence of scintillation is maximum, this is because there is an increase in eastward (westward) electric field at low latitude and equator during geomagnetic storm and it results high 𝑬×𝑩 plasma drift around the low latitude and magnetic equator region. In conclusion, phase scintillation is a night time phenomena.