I didn't travel the southern tier in march but I did travel it in the June 6th thru July 27th period.
I started in San Diego headed back to Sarasota Florida.
As soon as I come over the top of the hills 60 or so miles east of San Diego I was greeted with winds from the south/southeast that lasted until I reached Houston,Texas. Then it would change from east to west and back to from the southeast.
The winds early in the morning before the sun rises and starts the winds blowing again are real comfortable and make the distance more enjoyable.
Of course there always seems to be a constant wind, maybe the early riding was for my peace of mind regarding the heat. I discovered that talking to myself about the enviroment around me helps pass the time, and there is plenty of miles and time.
Out of houston I took a highway name ( 290 )Texas Hill Trail. That took me through Austin and across to just below the small town of Junction, texas.
I took this to advoid the trip all the way down to San Antonio then back up again to the same location. I traveled as straight a line as I could across.
I modified the route of the Southern Tier route provided by Adventure cycling.
Please plan to transport enough water to carry you more than 8 hours or 100 miles whatever comes first.
Water comes in three forms, bottled, from the hotel or undrinkable. Unless you have the chance to get it from a persons home water supply. The are a few small towns that will have public fountians. Of course a few reststops on the interstate have water. Some don't.
I'll explain if you email me off list or I will provide the info to this message board.
Jean Andre Vallerywww.2453.net