My hope is that there is some upside due to the climate here (vs. adding a garage on a property, say, in the southwest). 

Not enough single family homes to meet the demand (3.5 months of inventory on MLS).Climate vs Maine will be vastly different (hot and humid) but culture will be very similar.

The climate to do so has changed substaintially and the capital needed far more than in 1999. 

A couple things though...1) Houston is updating their floodmaps right now, with the revised rainfall risk (Atlas 14 that @Eliott Elias mentioned) it is expected to increase the number of homes in the FEMA mapped floodplain. 2) The 500-year is misleading, it means that in any given year there's a 0.2% chance that it will flood, but this is all based off of past data, it does not consider climate change.

If you are in a dry climate like Texas, mini splits. 

City populations expand and contract/collapse, and there are reasons for it -- government incentives for business, major transportation hubs, natural resources, climate, etc.

@Linda MalavetIn my opinion, in cold climates, fireplaces add value if it is a flip due to the opportunity they present to create a "wow"  factor.

So there's risks to consider in this uncertain rental climate.

What might that indicate in the current climate?

IMO price to rent and COC are snapshot investment looks and are in little way the primary investment climate indicators for healthy investments/markets by themselves.