Correct. If the weeds are not photosynthesizing rapidly, simazine will be very slow. It is useless for me to apply triazine or SU herbicides in weather that is not conducive to vigorous growth. The old chemistries like phenoxys or Quats are not as affected by bad weather.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738