Dipyrromethanes are stable at room temperature for 2 days.

But it depends what dipyrromethanes, normally dipyrromethanes with electron-withdrawing groups are stable for longer times than those with electron-donating groups as they stabilise the excess charge of the nitrogens.

I agree with Daniel, you can find some data about various kind of dipyrromethanes in the paper attached here.

sure actually, any paper from Jonathan Linsey is good place to look at when refering to dipyrromethanes