Based on the data available on the internet, his horoscope was prepared as follows:
Date of Birth: 17 Sep. 1950
Time of Birth: 11:00 am,
Place of Birth: Vadnagar.
Narendra Modi is born in Vrischik Lagna (Scorpio Ascendant). Mangal with Chandra makes him angry. Shani and Shukra in 10th house made him controversial with some groups. He have Raj Yoga, Gajkesari Yoga and Budhaditya Yoga - which are good for his political carrier. Current transit of Guru will give him Fame and Popularity during Election time. Shani is situated in the place of Surya, which can give a tough time as well as disappointment to his opponents. Surya and Ketu conjunction (Inauspicious Yoga) lead to his downfall and make some controversies before election. Shani transit in Tula - Sade Sati Panoti phase will confuse Modi in taking some big decision after election.
Conclusion: Narendra Modi has very high possibility of becoming the next PM of India. But He may be facing strong challenges and instability in his political career during 2014-15.