Average temperatures for the month of October fall from 71° and 50° on the 1st to 60° and 41° by Halloween. Indianapolis averages 3.12″ of rain this month and 0.40″ of snow.
We expect the MJO to remain in Phase 5 for the better part of the first half of the month. This, in conjunction with the positive PNA and negative EPO, will help drive the early cool pattern into the East. Note how that begins to change next week (the PNA goes negative and the EPO goes positive). This will likely erode a lot of the cool air and slowly, but surely allow warmer temperatures to penetrate east into the Ohio Valley beyond the 10th (give or take a day).
Note how the upper pattern follows suit:
The end result should be an unusually chilly start to the month that moderates towards mid and late month. Based on the MJO movement, there’s the potential of chill making a comeback just before Halloween (and into November), but this is a lower confidence call at this point. We’ll keep an eye on that as we move through the next few weeks. From a precipitation perspective, another very dry month is ahead. We’ll end up wetter than September, but still several weeks away from truly changing the precipitation pattern up from a holistic standpoint.
Here’s our official October Outlook. For central Indiana in particular, we expect an average to slightly above average temperature month (less than 1° above average) with well below normal rainfall.
