Possible Clues:

• Asian adder seen during unseasonal weather
• July through September, to a certain team?
• Late heatwave
• Fine weather for an Asian mathematician, perhaps
• Period of unusually warm weather (2 words)
• Warm period in autumn
• July for the Sioux? No, it¿s September for The Dubliners perhaps
• Unexpectedly warm period late in the year
• Native American with something to add when success comes late?
• Sounds like Sue has time to burn perhaps - it's success at last