"Just a quick question concerning the Hellenic Calendar. When it comes to the months and the festivals & observances within that month, are these observances, etc based off of seasonal events? Currently I am putting together a calendar for myself suited to the southern hemisphere and considering Australia's seasons are opposite to that of Greeces, would I need to swap around the months in which the festivals are held. For example traditionally Gamelion is in the Month of January & February which in Greece is Winter where as in Australia it is Summer so should I therefore adjust my calendar so that Gamelion is July & August?"
Hellenists on the Southern Hemisphere have two (well, three actually, but we'll get to that) choices: you can either follow the calendar of Greece and celebrate harvest festivals in Spring, or you can go against the grain, adapt the calendar to fit your seasons but remain half a year ahead/behind ancient Greece. Which one you choose depends on your priorities, I think. Let's work the pro's and con's of both scenarios.
Follow the original calendar: you have the benefit of being in line with the majority of Hellenists, which is awesome, but not essential. What does matter, though--at least to me--is that it is the calendar the Gods are used to. As a Traditional Recon, most of what I do, I do because the Gods were worshipped that way in ancient Hellas (or at least as close to it as I can get). As such, it matters to me that I perform a certain ritual on a certain date.
Adapt: so, you'll be out of sync with just about everyone, but most likely you will be in sync with local Hellenists--and that is a major plus. You might not be celebrating the festivals when the ancient Hellenist did, but at least you are celebrating them in the proper season.
In general, you can draw conclusions about the nature of the festivals by the God or Goddess to which the festival was dedicated. Demeter, obviously, is linked to agricultural festivals, Athena--usually--to the polis, or to a major historical event, etc. I am very happy I do not have to make this choice, but in my opinion, a blend of the two choices would be best. Craft a calendar where the agricultural festivals follow your seasonal cycle, and leave the polis and historical festivals where they are. Some will not blend well, but most, I suspect will fall into place quiet readily. I wish you the best of luck.
"How does the concept of Poseidon II work in the Hellenic Calendar. For example in Feb 2016 we have 29 days in the month rather than 28. So on the 29th would that be 1 Poseidon II and then March first being 2 Poseidon II?"
The ancient Hellenes had a problem: Hellenic months were either twenty-nine or thirty days in length, since the moon orbits the earth in roughly 29.5 days. Hollow months had twenty-nine days, full months had thirty. The ancient Hellens chose not to alternate the hollow and full months according to a set schedule ("Hekatombaion is a hollow month"), but instead, the duration of each month was declared just before month's end. The thirtieth day was always included; in a hollow month, the twenty-ninth day was left off of the calendar.
A full lunar year is 354 days long. Because the earth rotates around the sun in roughly 365 days, an extra month was inserted into the calendar every few years--usually every third year. This month was usually a repeat of the previous month, most frequently Poseideon, but there are references to repeats of Hekatombaion, Metageitnion, Gamelion, and Anthesterion. It is unknown if the festivals which fell in this month were repeated as well, if other festivals were held, or if no festivals were celebrated at all. How long this month was, depended on the previous years. The ancient Hellens had a tendency to repeat days to suit their needs, usually to postpone the arrival of a certain date. Assembly meetings, for example, were not held on festival days, so if the meeting was urgent, the previous day was repeated and the festival day postponed. A standard extra month would have been thirty-three days long, but it rarely was.
As far as I am aware, by the way, the next Poseideon II is from 22 December 2015 to 21 January 2015.
"Are there any hymns for the Agathós Daímon?"
I'm filling this one under 'calendar related' seeing as I am assuming the person who asked it probably wants to use it for His festival. As you might be aware, I have my own thoughts about Agathós Daímōn. On the second day of the new Hellenistic month, we give sacrifice to (the) Agathós Daímōn, on a day named after the 'Good Spirit'. The Agathós Daímōn was always a positive in one's life, and was generally seen as the source of personal or familial good fortune. Libations of (unmixed) wine were given to Him with each newly opened case of wine, and during feasts and symposium, Agathós Daímōn received the first libation. When crossing a snake on the road, it was also customary to pour out a libation, just in case it was a herald of Agathós Daímōn, or Agathós Daímōn Himself.
It's interesting to note that Agathós Daímōn is reported as receiving libations of unmixed wine, instead of the standard mixed libations of the Ouranic Theoi. This Khthonic aspect of His worship brings me to two possible explanations of the nature of Agathós Daímōn: a link to Zeus Meilichios ('the kindly one'), a Khthonic epithet of Zeus, and a link to Zeus Kthesios, the household protector. Artwork found at Lebadeia suggest a marriage between Zeus Meilichios and Agathe Tyche, and Zeus Meilichios--like Agathós Daímōn and Zeus Kthesios--is a snake God, often represented as one as well.
So, recapping: there is a good possibility that Agathós Daímōn is linked to Zeus and thus hymns to Him would work for Agathós Daímōn as well. I am partial to Orphic Hymn 72. There is also a short hymn from the Papyri Graecae Magicae, also known as the 'Greek Magical Papyri'. They are a body of papyri from Graeco-Roman Egypt, which each contain a number of magical spells, formulae, hymns and rituals. The materials in the papyri date from the 2nd century BC to the 5th century AD. The manuscripts came to light through the antiquities trade, from the 18th century onwards. One of the best known of these texts is the so-called Mithras Liturgy. It's quoted in Themis by Harrison.
"Give me every grace, all accomplishment, for with thee is the bringer of good, the angel standing by the side for Tyche. Therefore give thou means and accomplishment to this house, thou who rulest over hope, wealth-giving Aion, holy good Daimon. Bring to accomplishment and incline to me all the graces and divine utterances."