If I remember correctly, you're in San Antonio, right? The only major flooding that I remember in San Antonio in September/October was in 1998, and I'll let the natives who've stayed in San Antonio correct me on that, if necessary.

My yard, north of Dallas, has the same problem. We installed a french drain to help the backyard and I dug a trench in 2007 to start a french drain for the side yard when I feared that all the rain was going to drown the pecan there.

My choice would be to go ahead and plant, counting on Murphy's Law to work. If you do get too much rain and the plants start looking bad, at 1-3 months in the ground, their root systems shouldn't be too big and you can pull them back out and wait the flooding out. At worst, you have to dig the plants out and put them into something else for a couple of weeks, then replant. At best, Mother Nature helps you keep them watered for the winter.

Good luck! I hope y'all start getting enough rain to refill the aquifer!

Yes, San Antonio. We had some significant flooding in 2002 as well. 2007 wasn't bad, but the continual rain gave me a small lake ;)

French drains are in our longer term plan, but not something I'll be doing anytime soon. I'm hoping that by leveling the yard we'll have less issue with all the little ponds forming, but we'll see.

I think I'll plant anyway. But maybe not too much.

Just go ahead and plant. Who really knows what would happen? I was in New Braunfels a few weeks ago and I was at Schilterbahn and I was amazed to see the sign on the wall of the motel showing flood level during October of 1998 when it rained as much as 30 inches somewhere in that region. I fondly remember 2002 flooding. I was in Austin coming in from Houston for river trip in New Braunfels but it was bad timing because it was pouring in New Braunfels big time. Needless to say, it was canceled.

There's no guarantee about what will happen this fall. Don't believe everything you hear. Supposedly there is more rain during fall when El Nino is in force. The flooding part of it is just pure speculation. As far as I'm concerned the same weather technology that can't seem to reliably forecast the weather 3 days from now certainly can't tell us that much about weather this fall. Hopefully we will at least return to a normal rainfall pattern. A bit more than that would be nice. The aquifers and lakes need filling, so I'll just hope for the best. San Antonio and a lot of certain Hill Country areas are known for flash-floods, the most dangerous kind of flooding. People should find out where the worst floods usually occur and avoid those areas. And then keep in mind that it can on rare occasion happen even in the safest areas. I have held off on planting to some extent after the spring rains stopped. I'm just trying to be cautious and wait until all the heat is over and enough rain happens to be hopeful. We haven't seen any rain other than extremely tiny amounts for quite some time. I long for rain, dream about rain, I get down about not getting it...but 2002? People died...some lost homes or survived really nightmarish flooding. Not something I'd ever want to see happen again.

Ignore the El Nino. Less hurricanes, BUT the 1900 storm-El Nino, Carla? El Nino, 1915 El Nino, as a matter of fact most of the biggest storms seem to hit during El Nino.
And Alvin still holds the record rainfall in 1979 from a tropical depression. And my neighborhood hadn't flooded in 108 years, so you just never know.
Tally HO!