The Tamil Solar Calendar
The 12 Tamil months are solar months — each month begins when the Sun enters a new zodiac constellation (Rasi). This makes Tamil months precisely astronomical: the start date of each month is calculated from the Sun's actual position in the sky, not from a fixed date on a civil calendar. Tamil months can begin on different Gregorian dates each year by a day or two depending on the Sun's exact speed.
The Tamil month names are some of the oldest continuously used astronomical terms in any living language — most are named after the Nakshatra the full moon falls in during that month.
All 12 Tamil Months — Complete Reference
| # | Tamil Month | Tamil Script | Rasi (Zodiac) | Approx. Gregorian | Key Festival | Character |
|---|---|---|---|---|---|---|
| 1 | Chithirai | சித்திரை | Aries / Mesham | Apr 14 – May 14 | Puthandu (Tamil New Year) | The year begins. Hot season starts. Named after Chithirai Nakshatra (Spica). |
| 2 | Vaikasi | வைகாசி | Taurus / Rishabam | May 15 – Jun 14 | Vaikasi Visakam (Murugan) | Peak summer in Tamil Nadu. Named after Vaikasi full moon falling in Visakam Nakshatra. |
| 3 | Aani | ஆனி | Gemini / Midhunam | Jun 15 – Jul 16 | Aani Thirumanjanam | Pre-monsoon heat. June solstice falls in this month. Named after Aani full moon in Anusham. |
| 4 | Aadi | ஆடி | Cancer / Kadagam | Jul 17 – Aug 16 | Aadi Perukku (river festival) | Southwest monsoon. Rivers flood. Sacred to Amman (goddess) temples. Named after Ayilyam Nakshatra. |
| 5 | Aavani | ஆவணி | Leo / Simham | Aug 17 – Sep 16 | Krishna Jayanthi; Aavani Avittam | Monsoon easing. Named after Avittam Nakshatra. Thread ceremony month for Brahmins. |
| 6 | Purattasi | புரட்டாசி | Virgo / Kanni | Sep 17 – Oct 17 | Navarathri; Saraswathi Puja | Post-monsoon. Saturn's sacred month — many skip non-vegetarian food. Named after Poorattathi Nakshatra. |
| 7 | Aippasi | ஐப்பசி | Libra / Thulam | Oct 18 – Nov 16 | Deepavali (Festival of Lights) | Harvest begins. Deepavali falls in this month. Named after Ashwini Nakshatra at full moon. |
| 8 | Karthigai | கார்த்திகை | Scorpio / Viruchigam | Nov 17 – Dec 15 | Karthigai Deepam (fire festival) | Cool season. Pleiades (Karthigai stars) at their highest. The great fire festival Karthigai Deepam falls here. |
| 9 | Margazhi | மார்கழி | Sagittarius / Dhanusu | Dec 16 – Jan 13 | Thiruvempavai; Thiruvaembavai | Holiest Tamil month. Cool and misty. Daily dawn rituals. Andal's Thiruppavai hymns sung. Most sacred for Vaishnavites. |
| 10 | Thai | தை | Capricorn / Makaram | Jan 14 – Feb 12 | Thai Pongal (harvest); Makar Sankranti | Winter. The Sun turns northward (Uttarayana) — Sun enters Makaram. Pongal, the greatest Tamil festival, falls here. |
| 11 | Maasi | மாசி | Aquarius / Kumbam | Feb 13 – Mar 13 | Maasi Magam (sea festival) | Late winter. The full moon in Magam Nakshatra — Maasi Magam — is especially auspicious for sea bathing at coastal temples. |
| 12 | Panguni | பங்குனி | Pisces / Meenam | Mar 14 – Apr 13 | Panguni Uthiram; Ugadi | The final month. Spring arrives. Panguni Uthiram festival in Uthiram Nakshatra. Pre-New Year rituals prepare for Chithirai. |
The Two Types of Tamil Months
The Tamil calendar tracks time using two parallel month systems, both running simultaneously:
- Solar months (Saura Masa) — the 12 months above, each defined by the Sun's zodiac position. Used for all civil, agricultural, and annual calendar purposes.
- Lunar months (Chandra Masa) — months defined by new moon to new moon (~29.5 days), used for calculating Tithis, Ekadashi fasts, and festival precise timing. Lunar months have Tamil names too (Chithirai, Vaikasi etc.) but begin and end on new moon days rather than solar entry.
This dual-month system is why the Tamil calendar is called lunisolar — it tracks both the Sun and the Moon simultaneously, using each for different purposes.
Margazhi — The Holiest Month
Of all 12 months, Margazhi (Sagittarius, December–January) holds the most sacred place in Tamil tradition. According to the Bhagavad Gita (Chapter 10, verse 35), Lord Krishna himself declares: "Among months, I am Margazhi." During this month, Tamil devotees wake before dawn every day for special rituals, sing the Thiruppavai hymns of Andal, and visit temples in the cool mist of the pre-dawn hours.
Astronomically, Margazhi is the month when the winter sky is clearest and most spectacular — Orion (home of Thiruvathirai / Betelgeuse), the Pleiades (Karthigai), and the full Milky Way arc are all visible on long, dark nights.
Thai Pongal — The Sun Turns North
Thai Pongal (January 14) is the greatest Tamil harvest festival, celebrated on the first day of the month of Thai when the Sun enters Capricorn (Makaram). This marks Uttarayana — the Sun's northward journey, when days begin lengthening and the agricultural new year begins. The festival involves boiling the first rice of the harvest in milk outdoors under the Sun — a direct act of solar worship that has been performed for over 2,000 years.
Why Tamil months are more astronomically precise than Gregorian months: Gregorian months are administrative divisions of no astronomical significance — they do not correspond to any celestial event. Tamil months, by contrast, each begin at an exact astronomical moment: the Sun's entry into a zodiac constellation, calculated fresh each year from the Sun's actual position. Every Tamil month date is a real astronomical event.