While later Hellenists revered Apollon directly associated with the sun, this is not something that plays a great importance in my worship of him. Yes I recognize he has connections to Helios and favors Helios, but he also has significant connections to the moon in his cult outside of poetics and to the stellar bodies of the heavens, certain heavenly events being ones that were said to indicate the seasons for his festivals (as well as important agricultural and husbandry themes). For instance there are scholars who suggest that the rising of certain stars (likely Gemini, a sign that he has been astrologically linked to anciently in his worship, perhaps sharing alike certain connections with the Dioskouri who represent said body) was the actual start of Thargelia…around the 21st of May. And as for his return to Delphi, that this was signified by the rise of the constellation of Delphus (which was visible later in Delphi due to the mountains). Combined with certain festivals that were focused on fullmoons (such as Hyakinthia and Karneia among the Spartans) it is no wonder that we have a very convoluted heavenly array associated with Apollon that cannot be narrowed down to “sun god” but is often done due to historical precedent of this occurring during the Hellenistic period.
Rather, I would say that anciently Apollon had more to do with the weather. We find in the Iliad that Apollon is directly responsible for the winds with which he uses paired with the rains of Zeus and torrents of Poseidon to break down the wall of the Hellenes that had been erected without tribute to them. The association Apollon and Poseidon have with walls (and foundations) is probably due to the volatile nature of weather and to secure safe haven by their mercy and grace behind fortifications as we build our homes and dwellings. On a larger civic level this takes us further into walls and gates as fortifications against possible hostile forces. Certainly the destructive tendencies of Apollon and Poseidon when dealing with the nature climate was probably very closely tied to this. Apollon as a god associated with the weather could be destructive or he could be kind and merciful and provide the right growing conditions in a balance of moisture and dry heat to ripen grains and fruits. I have written before of my associations of Apollon with Iakkhos, as a son of either Demeter or Persephone (as we have it both ways) and clarified by Diodoros Siculus’ narration on the origin of the mysteries in Egypt with Apollon as the child of Isis and Osiris. Perhaps it is through this association that we see the real firm stirrings of a solar identity of Apollon through his loose Egyptian associations. However, my perception on this is that Diodoros made this an example for explaining how the mysteries operated in Hellas rather than making any real parallels with Egyptian religion. Apollon as Iakkhos is the companion/child of Demeter, the announcer of the mysteries of Dionysos, reveler in those mysteries (as the Orphic hymn calls both himself and Artemis as being Bakkhic…likely for good reason here), and proclaimer of Persephone whom we see rising in the Spring on a Delphic vase greeted by Dionysos, Pan and Apollon.
Certainly the Doric station of Karneios with his pinecone, a natural barometer, indicates a god who is foreseeing and attending to the season of growth while keeping his gaze on the rainy season to come. In fact this plays a very pivotal point with Apollon’s nature as a prophetic god if we consider that Apollon is attending to weather patterns that would ideally lead to a ripening of grain and plant life to provide seed for the next year’s crops as well as be a form of sustenance, we can see that planting and harvest would be very much in keeping with his foresight. It may have originated agriculturally. When should I move my herds to different pastures? When should I harvest the grains? It would all play out, probably in part by the movement of the heavens which priests would have kept a strict eye on. As agriculture is very closely tied with civilization (after all we find earth goddesses from Gaia, to Themis to Demeter all attributed with crafting laws) it is not hard to see how things would extend from the cultivation of the earth to a cultivation of spirituality and humanity (via the arts). He is the leader of the Muses as well as the leader of pastoral nymphs for this reason….it is interrelated. Health and wellbeing being another facet to this overarching compass. He is destroyer…and provider. He is sustainer and keeper of harmony and balance. He is a guardian of laws as we find at Olympia, those same laws attributed to goddesses of the earth. That is because his role impacts all the way through….and this makes his relationship with Demeter and Persephone so vital.
Other factors of course indicate his weather associations, aside from being called their king by the Dioskouri in the play Elektra, he is also considered one of few gods permitted to use the thunderbolts of Zeus (along with Athena), which would account for comments about prophets searching for Pythian lightening to indicate that they begin their journey from Athens to Delphi. His winds can bring in the abundant rain clouds of Zeus or push them away, he can howl with the winds or calm them. The very presence of the winds in relation to him mythically puts further weight behind this that the winds would be acting in his myths and cult, notably the two extremes (the two original seasons as Pausanias tells us) Winter and Spring….the winds of those seasons being Boreas and Zephyr. We also know that in Hera’s temple in Argos that in a hall Pausanias notes the presence of four statues facing each other…Demeter and Kore at one side facing the statues of Apollon and Artemis. This is not to mention Apollon’s seasonal presence in the temple of Demeter and Despoina in Arkadia.
It is for all these reasons and more that I consider the relationship Apollon has with Demeter to be one of the more important ones among the gods, and a reason why Demeter’s presence is on the upper tier of his shrine on the other side of Artemis from himself. This actually adds an interesting dimension to Thargelia celebrations in which in Athens on the sixth day of Thargelion, whereas we find no references to Artemis, we find that Demeter was honored as Chloe (the green) likely part of the festivities of the harvest of the green ears of grain at the nativity of Apollon.
I would wager to guess that this is part of why Apollon when adopted by the Etruscans and Romans did not carry significant solar characteristics. Most scholars have suggested it was because of popularity of a local sun god Sol, but it is plausible that it had more to do with being adopted before his associations with the son in the Hellenistic period got a good foothold. In fact, his appearance in the company of various scenes in Etruscan art indicates more of a supportive role, as a weather/season-related divinity would have versus that of a solar god. Such as present at the birth of Fulfuns (Dionysos), and the suckling of Hercle (Herakles), or even prophet activity of other Etruscan deities. As being paired in direct mirroring with Artemis is quite likely that Etruscans when they adopted Apollon viewed Aplu and Arteme as being mirroring each other and having directly to do with similar activities….usually involved with nature and the translation of the activities of nature into the welfare of civilization.