Predicting My Marathon Finish

I always like trying to predict my finish times. Whether it's a 5K road race or a 100 mile trail ultra, it's fun to think about best and worst case scenarios. It's never easy, often the predictions are wrong, but it's a neat excercise. With the Illinois Marathon only 9 days away, it seems about the right time to be predicting my finish time. And you can play along too!

To provide some context, here are predictions based on the McMillan Running calculator:

My most recent 5K time (20:28) predicts a 3:19:26 marathon
My most recent half-marathon time (1:32:35) predicts a 3:14:51 marathon
My most recent 50-mile time (9:04) predicts a 4:05:12 marathon

My goal is to qualify for Boston. I need a 3:30. Based on my 5K and half-marathon finishes (about 6 months ago), I should easily be able to achieve a 3:30 marathon. I'm probably not in as good of shape as I was back then...at least for pure speed. I could probably run a 20:45 5K and a 1:34 half-marathon now.  I could likely run a faster 50-mile trail race (same conditions). What does that mean for my April 25th marathon?

If weather is good (cool, overcast, and no wind), I predict a 3:29 marathon. Just enough to qualify for Boston, but probably not enough to actually register and get into the race! (You often need about 1.5-2 minute cushion to get into Boston.)  That time would still be a PR, but it would be disappointing. Very disappointing.

If the weather is warmer, or otherwise not ideal, I think I'm looking at around a 3:35 finish. Solid, but not what I want or need.

So, how fast, or slow, do you think I will run at the Illinois Marathon?