I find Morels in Texas as early as February. Temp base mostly. When nights are about 45 deg or above and days are in the 60's. Look for elms, ash, beech, and oaks (oaks later in the season). I do find stands of morels around cedars as long as they are mixed with some hardwoods. Usually late in the season as well. Grey morels pop up first...along with blacks...very hard to see, as they blend in well with the leaf litter. Then later the goldens and blonde colors shows up....even Ray Charles can see these, as they are very large and stick out like a sore thumb. Once temps reach into the upper 70's in the day, they start to fade out. Rule of thumb...pick them when you see them. I haven't seen much luck in them getting bigger as the days go by. I pick on my personal property so I'm not rushed.