The one year I ran Syttende Mai, the rolling 20mile race from Madison to Stoughton when I turned 40 I was hoping to get about 2:02, but I was only 10 weeks into a racing comeback.
That year (1990) it was pouring rain, 44 degrees F (not WC), and 20-25mph wind from the SE (with higher gusts), i.e., a dead-on headwind. Because it was mid-May in Wisconsin were are not many leaves on the trees so there was little wind break. I ended up at 2:06 even though I was hampered by a sore quad from running a hard 20k just before (only when I ran that so well did I know I was really doing SM). The quad cost me 2+min the last 3+ miles.
In the trials race the trees are still fairly 'leafed' and there are more trees and there is no net running into the wind. It will probably have more effect on time by changing strategy (so you do not lead and break the wind for others) than from the slowing effect during the time spent into the wind.
The forecasts at 30mph were a different matter.