I thought the consensus was summer after dry spells the plant produces more alkaloids. Which would be scientifically consistent with most plants anyway iirc.
I gotchya! 'Haven't been able to be systematic about it, but two post-rain day harvests were very....i do believe it rises above where it began, some time days after rain, i always thought it was the delay in surface nitrogen compounds making their way to the roots and being absorbed, or just an overcorrection making new DMT to replace what the rain leeched away....

...not worth the materials and time put into it...