Baird, M.B., O'Connor, R.E., Williamson, A.L., et al. (2010). The Impact of Warm Weather on Mass Event Medical Need: A Review of the Literature. (Abstract only.) American Journal of Emergency Medicine. 28(2):224-9.
From an in-depth literature review, the authors found that most studies found a positive relationship between heat/humidity and the frequency of patient presentation. In addition to the literature review, the authors propose an algorithm for predicting patient volume at mass events.