The Modern Persian months are based on religious and Zoroastrian months. As the data shows ** the old Persian months are  based on the climate change and farming events. Massoume Price* suggests that these months are analogous to the Babylonian months. Still there are some connections between Old and New Persian months (like Fire [worshipping]), but the names of seasons of spring and Winter in Persian are similar to the vahar and Zam months in old Persian. 
The present Modern Persian months were not even used by Cyrus and Dariush (the kings of Persia) in their inscriptions and this change has happened in a later time. 

* Price, Massoume, "Iranian months: Origin of the names", http://www.persianoutpost.com/htdocs/IranianMonths.html  
**.Lecoq, Pierre, Les inscriptions de la Perse achéménide, Gallimard, 1997

The Zodiac  and Persian months are contrasted in the following table :

Zodiac	Avestan	Modern Persian*	Old Persian**
Aries	Fravashi	Farvardin	Âdu-kanaisha (channel-digging)	1.
Taurus (Ram)	Asha Vahishta	Ordi-behesht	Dhûra-vâhara (Bahar)	2.
Gemini (Twins)	Haurvatat	Khor-dad (water-protector)	Dhaigar-chi (garlic-collecting)	3.
Cancer (Crab)	Tishtra	Tir(Swift) (rain protector)	Garma-pada heat-moment	4.
Leo (Lion)	Ameretat	[a-]Mor-dad	*Dhurna-baxshi ?-giving	5.
Virgo (Virgin)	Khshatra Vairya	Shahr-ivar	*Garma-baxshi heat-giving	6.
Libra (Balance)	Mithra	Mehr	Bâga-yâdi (God-worship)	7.
Scorpio (Scorpion)	Aban	Ab-an (Water)	*Vrk-aj/zana (wolf-driving)	8.
Sagittarius (the archer)	Atar	Azar	Âchi-yâadiya (Fire-worship)	9.
Capricorn (the goat)	Ahura Mazda	Dey[dar]	A-nâma-ka without-name	10.
Aquarius (water bearer)	Vohu Mana	Bah-man	*Zam-ima (Winter)	11.
Pisces (fish)	Spenta Aramaiti	Esfand[-armatia]	viyaxna digging	12.

Table 1: Zodiac and Persian Months

The persian calendar is a solar calendar, originating from the zoroastrian calendars of pre-islam Persia.
The persian months correspond with european dates as follows :

The last five days of the year are known as ‘panj-i-meh’ "the greater five days." These are the days of the Gathas which constitute the Hamaspathmaedhem Gahambar and are the last five days of a Zoroastrian calendar year ; they are named after the five Gathas :

1. Ahunavaiti

2. Ushtavaiti

3. Spentamainyu

4. Vohukhshathra

5. Vahishtoishti

It is during the 5 days of the GATHAS, that Ahura Mazada (God) spoke to the Great teacher and enlightened Him. In Sarosh Yasht III it is stated that Sarosh Yazad, Sraosha, was the first to chant the five Gathas

The five Gathas are as follows:

I         Ahunavad (Yasna 28 - 34) (possessing the power of the Ahunavar);

II        Ushtavad (Yasna 43 - 46) (possessing Divine Happiness and Joy);

III       Spentomad (Yasna 47 - 50) (possessing devotion/piety);

IV        Vohu Khshatra (Yasna 51) (possessing Good Power, in Peace !)

V         Vahishtoist (Yasna 53) (possessing Best Spiritual Riches :Righteousness).

 
 

The 5 Gahs

THE GAHS. 

The Gâhs are the five divisions of the day :

1.      The Hâvani from 6 to 10 A.M.,

2.      the Rapithwina from 10 A.M. to 3 P.M.,

3.      the Uzayêirina from 3 to 6 P.M.,

4.      the Aiwisrûthrima from 6 to 12 P.M.,

5.      the Ushahina from 12 P.M. to 6 A.M.

The changeover from each period to the next is marked by the offering of boy* to the Fire, while recitating specific prayers, which can be found in the Zend Avesta, and which are called Gâhs, because of the practice of chanting them at the different fixed times in the day. In this way there is a Hâvani Gâh, a Rapithwina Gâh, a Uzayêirina Gâh, an Aiwisrûthrima Gâh and an Ushahina Gâh in the Zend Avesta.

*boy (Phl.):

lit. 'offering incense', a ceremony of offering sandalwood and frankincense to the consecrated fire during each of the five watches of the day. (Var. 'bui, nirang-i bui dadan, boy dadan')

Gahambars

• Maidyozarem ('mid-spring' feast) Apr30-May4
• Maidyoshahem ('mid-summer' feast) Jun29-Jul3
• Paitishahem (feast of 'bringing in the harvest') Oct12-16
• Ayathrem ('bringing home the herds') Oct12-16
• Maidyarem ('mid-year'/winter feast) Dec31-Jan4

Other important festivals

• Hamaspathmaidyem (feast of 'All Souls') Mar16-20
• Noruz (New Years) Mar21
• Jashan-e Mihragan October 1
• Jashan-e Tiragan July 1
• Jashan-e Sadeh Dec 11

Persian New Year - Noruz
(No ruz, Nowrouz, Nowruz, Nooruz)

NEW YEAR TABLE

Norooz, the iranian new year, is celebrated on the first day of Spring, the 21st of March, for more than 7000 years.
Fifteen days before Norooz, a special cover is spread on to the Persian carpet or on a table in every Persian household. The table is  set which, in iranian, is called "Sofreh ye haft sin". "Haft sin" means seven "S".
This ceremonial table is called cloth of seven dishes, (each one beginning with the Persian letter cinn). The number seven has been sacred in Iran since the ancient times, and the seven dishes stand for the seven angelic heralds of life - rebirth, health, happiness, prosperity, joy, patience, and beauty.

1. Sabzeh or sprouts, usually wheat or lentil representing rebirth.
2. Samanu is a pudding in which common wheat sprouts are transformed and given new life as a sweet, creamy pudding and represents the ultimate sophistication of Persian cooking.
3. Seeb means apple and represents health and beauty.
4. Senjed the sweet, dry fruit of the Lotus tree, represents love. It has been said that when lotus tree is in full bloom, its fragrance and its fruit make people fall in love and become oblivious to all else.
5. Seer which is garlic in Persian, represents medicine, health.
6. Somaq sumac berries, represent the color of sunrise; with the appearance of the sun Good conquers Evil.
7. Serkeh or vinegar, represents age and patience.

Furthermore, other things you can place on the table which may not begin with letter 's' but that have significance. For instance, a book, symbolizing wisdom,  a mirror to symbolise destiny, candles to represent happiness . two flowers, Sonbol and Laleh (hyacinth and tulip) symbolize spring, the revival of the nature. Red fishes in a small aquarium, goldfish to represent life. Painted eggs stand for fertility of people and land, a jar of water to symbolize purity and freshness,  Sekeh, coins representing wealth, prosperity.
An orange is placed floating in a bowl of water representing the planet earth floating in space. At the exact time of new year, the orange starts to turn in the water.
The table may also include an orange in a bowl of water to symbolize earth .

Frawardigan

 

Frawardigan (Phl.):

During the last ten days of the religious calendar, the farohars (farvardin, fravashis) of the departed are remembered, aka All-Souls days, Mukhtad. (Originally 'rozan Frawardigan'.)