There are clear indications of temporal relationships between different surveillance signals, with PAN consistently giving a 1-day lead over ED for ILI. The strong relationship between temperature and ILI cases during the 2009 H1N1 pandemic is most likely coincidental since the onset in Champaign County coincided with the change of season in September/October. The lack of a relationship between ILI and weather during the 2008 seasonal outbreak remains to be understood.