(Portland, OR) -- TriMet passengers on MAX and WES need to prepare for possible delays during the high heat today. When temperatures reach at least 100 degrees, the trains need to slow down. TriMet has made improvements to adjust for heat effects on power wires and trackways, but MAX is limited to 35 miles an hour at temperatures over 100 and WES is limited to 40 miles an hour. Passengers should plan for possible delays in the afternoons.