Here is the list of Hindu festivals in April 2013. April 2013 coincides with Chaitra month & Vaishakh month in North Indian Hindu calendars; Phalgun Month and Chaitra Month as per Amavasyant calendars followed as per Marathi, Gujarati, Kannada & Telugu Panchangas.
Vasant Navratri (Chaitra Navratri), Ugadi (Telugu and Kannada New Year day), Gudi Padwa (Marathi New Year day), Cheti Chand (Sindhi New Year day), Navreh (Kashmiri New Year day), Chithirai Vishu (Puthandu, Tamil New Year), Vishu in Kerala (Malayalam Zodiac New Year), Pohela Boishakh (Naba Barsha 1420, Bengali New Year), Bohag Bihu (Assam New Year), Sri Ram Navami Festival, and Hanuman Jayanti (Chaitra Purnima) are the important festivals in April 2013.
Here is the list of some other Hindu festivals & Auspicious days in April 2013
April 1, 2013: Eknath Sashti
April 2, 2013: Mangaladevi Temple Rathotsava Mangalore
April 3, 2013: Anagha Lakshmi Vrat, Kalashtami, Sri Shivaji Maharaj Punyadin, Sant Saraswatidas Punyatithi. Sheetala Ashtami.
April 5, 2013: Hanuman Prasad Poddar Punyatithi (Founder of Gita Press)
April 6, 2013: Papmochani Ekadashi. Panchak begins.
April 7, 2013: Pradosh. Varuni Yog. Adikeshav Darshan at Varanasi.
April 8, 2013: Shivratra
April 9, 2013: Darsh Amavasya. Meerut Navchandi Mela at Uttar Pradesh
April 10, 2013: Ugadi Amavasya, Dharmaveera Sambaji Maharaj Balidaandin; Sri Rajarajeshwari Temple Utsava Polali. Panchak ends.
April 11, 2013: Ugadi, Dharmashakti Sen Vardhanti Utsava; Dr Hedagevara Jayanti; Allamaprabhu Jayanti. Gudi Padwa. Cheti Chand. Nava Samvarotsav. Vasant Navratri begins. Sri Rama Navaratri begins.
April 12, 2013: Sri Swami Samarth Prakatdin Akkalkot. Sindhara Duj.
April 13, 2013: Matsya Jayanti, Gangaur, Jalianwala bagh Smrutidin, Sant Meerabai Punyatithi. Gauri Tritiya (Teej). Gangaur Puja ends.
April 14, 2013: Baisakhi. Vinayak Chaturthi. Chithirai Vishu / Puthandu (Tamil New Year), Vishu (Malayalam New Year), Vishuba Sankranti (Odisha New Year day)
April 15, 2013: Pohela Boishakh (Bengali New Year), Shri Gurudatta Jatra Bugate Alooru Hukkeri. Shri Rama Rajyabhishek Mahotsav. Bohag Bihu (Assamese New Year day).
April 16, 2013: Sri Basaveshwara Jatra Hitani Gadahinglaja. Vasantiya Surya Shashti (Chaitra Chhath Puja), Guru Harkrishnan Punyatithi. Guru Angaddev Punyatithi.
April 17, 2013: Navali Bhogapuresha Rathotsava; Sri Siddhalingeshwara Swamy Rathotsava Yediyur. Basanti Puja in West Bengal.
April 18, 2013: Durgashtami, Vasantik Durga Puja, Shri Saibaba Utsav begins in Shirdi Temple, Bhavani Jayanti, Damodar Chapekar Balidaandin. Gurupushyamrit Yog.
April 19, 2013: Sri Ramnavami, Ayodhya Parikrama, Swaminarayan Jayanti at Akshardham in Gujarat. Samarth Ramdas Swami Jayanti
April 20, 2013: Sri Swaminarayan Jayanti; Siddharudha Swami Jayanti
April 21, 2013: Chaitra Vijayadashami, Shri Saibaba Utsav ends at Shirdi Temple, Shalivahan Jayanti. Dhwajarohana in Chittapur Matha Shirali; Sri Koravara Pranadevara Rathotsava
April 22, 2013: Jogeshchandra Chatterji Janmadin; Madhukeshwara Rathotsava Banvasi; Kamada Ekadashi
April 23, 2013: Ananga Vrat. Bhaum Pradosh Vrata.
April 24, 2013: Mangal Pandey Balidaan din; Satya Saibaba Punyatithi Puttaparthi (As per date)
April 25, 2013: Hanuman Jayanti, Chaitra Hunnime, Khandagrasa Chandra Grahan, Chaitra Purnima.
April 26, 2013: Chandralamba Mayuravahana Utsava Sannathi; Senapathi Tatiyatope Balidaandin; Kunvarsimha Balidaandin. Grahan Karidin.
April 27, 2013: Chandralamba Parameshwari Gajavahana Utsava Sannathi; Sridhara Swami Punyatithi. HH Dattatreya Joshibaba Punyatithi at Mumbai.
April 28, 2013: Sankashti Chaturthi, Pujya Ratnakara Marathe Punyatithi.
April 29, 2013: Sri Brahmi Durgaparameshwari Rathotsava Kamalashile; Sati Anasuya Jayanti.
April 30, 2013: Macchindranath Punyatithi. Rashtrasant Tokdoji Maharaj Jayanti as per date. Agadi Sri Seshachala Maharaj Jayanti
Here is the list of some other Hindu festivals & Auspicious days in April 2012
April 1, 2012: Sri Rama Navami, Bhagavan Swaminarayan Jayanti, Vasanta Navratras Samapthi (Chaitra Navratri ends), Devi Damanotsav, Durga Navami. Ramrajya Mahotsav. Jaware Visarjan
April 2, 2012: Dharma Dasami (Dharmaraja Dashami), Shalivahana Jayanti
April 3, 2012: Kamada Ekadasi, Sri Krishna Dolotsava, Lakshmi Narayana Dolotsava (Lakshmikanth Dolotsav), Maharshi Damana Puja, Phuldol Gyaras in Vrindavan
April 4, 2012: Vamana Dwadasi (Madan Dwadasi), Vishnu Damanotsava, Ananga Trayodasi (Anang Vrat), Pradosha Puja, Varaha Jayanti
April 5, 2012: Panguni Uthram in Tamil Nadu, Shiva Damanotsava (Shiva Damanak Chaturdasi), Kamotsav, Nrusimha Dolotsava, Hanuman Jayanti Ka Upvas. Hatkeshwar Jayanti
April 6, 2012: Shachi Indra Damana Puja, Madana Purnima, Chaitra Purnima, Maha Chaitri, Hanuman Jayanti (Hanuman Vijayotsavam), Sarva Devata Manotsava, Agni Savarnika (Rouchyaka) Manvadi, Vishwambharadhuta Dattavatara Anvadhanam, Bhargavaraka Vratham, Chitragupta Puja. Satyavrat Purnima, Chatrapati Shivaji Maharaj Punyatithi. Vaishakh Snan begins in North India. Shri Jyothirlinga Yatra Kolhapur
April 7, 2012: Pathala Vratham, Vaishakh Maas begins in North Indian Hindi calendars. Sri Mahalakshami Rathotsava Kolhapur. Dafalapur Ekaveera Devi Yatra. Hanuman Yatra in Nave Pargaon (Maharashtra). Kacchapavatar. Sri Ekalingji Maharah Utsav. Vishnu Puja with Tulsi leaves.
April 8, 2012: Asha Dooj (Aso Dooj)
April 9, 2012: Sankashta Hara Chaturthi
April 10, 2012: Matsya Jayanti, Sati Anasuya Jayanti, Chandragupta Maurya Jayanti
April 11, 2012: Sri Chandla Devi Utsav
April 12, 2012: Bhanu Saptami
April 13, 2012: Chithirai Vishu (Varusha Pirappu, Puthandu, Tamil New Year), Mesha Sankranti, Nandana Nama Samvatsara begins in Solar calendar, Anaghashtami, Shitalashtami, Vishuvath Punyakalam, Sujanma Vapthi Vratham, Kalashtami. Baisakhi Parva. Shitla Pujan. Charak Puja in Bengal.
April 14, 2012: Vishu in Kerala (Malayalam Zodiac New Year), Chandika Navami Vrat. Pohela Boishakh or Naba Barsha 1419 (Bengali New Year), Bohag Bihu (Assamese New Year)
April 15, 2012: Panchak begins
April 16, 2012: Smarta Varudhini Ekadasi, Sri Vallabhacharya Jayanti
April 17, 2012: Vaishnava Varuthini Ekadashi, Manjula Dwadasi, Tripushkara Yogam (Dwadasi tithi in Purvabhadra Nakshatram)
April 18, 2012: Varaha Jayanti, Pradosh Vrat
April 19, 2012: Masa Shivaratri, Vrishabhayanam, Saur Greeshm Ruthu begins. Samarth Guru Akkalkot Swami Punya divas.
April 20, 2012: Pitru Karya Darsh Amavasya, Panchak ends
April 21, 2012: Shani Amavasya, Padmaka Yoga, Mela Shani Shingnapur in Maharashtra, Sri Sukhdev Muni Jayanti
April 22, 2012: Vaishakh Snan arambh in South India, Chandra Darshanam, Tripushkara Yoga, Rushi Parashar Jayanti, Devdamodar Tithi in Assam
April 22, 2012: Chatrapati Shivaji Maharaj Jayanti (Parampara se – As per tradition)
April 24, 2012: Akshaya Tritiya. Akha Teej. Ganga Snan, Parashurama Jayanthi, Padma Kalpadhi, Treta Yugadi, Chandan Yatra in Puri Jagannath Temple, Chandanotsavam in Simhachalam Temple, Sri Basaveshwara Jayanti. Rohini Vrat. Matangi Jayanti
April 26, 2012: Sri Shankara Jayanti (Birth Anniversary of Sri Jagadguru Adi Shankaracharya), Sri Surdas Jayanti.
April 27, 2012: Putraprapthi Vratham, Sri Ramanuja Jayanti. Chandan Sashti in Bengal. Nrusimha Navratri begins
April 28, 2012: Sri Vidyaranya Jayanti, Gangotpatti, Kanyakumari Avataram, Tripushkara Yogam, Ganga Saptami Ganga Pujan. Gangavataran. Chitragupt Jayanti Puja.
April 29, 2012: Pushyarka, Devi Maa Bhagalamukhi Jayanti, Mela Bharatrihari Alwar (Rajasthan)
April 30, 2012: Guru Moodam begins, Janki Navami (Sita Navami)