yea humidity is importent here, if possible keep it above 50% (60-80% is actually to prefer here)
temps is also important but as long its around 75-80F you good ..
more important is the soil temps (why some Ppl. use heating mats in there domes) as you looking for root grow at this stages, if you can keep Temps higher in the soil the above you will get a fast root grow going and get your plants ready for Veg fast..
but agin this is not so important, you can easily get a good result with a RH on Etc. 40% and normal room temps with out a dome or heating mats, just not so fast ..
I germinate mine in the soil with temps around 75F and a RH on 40-50%, no dome or heating mats or anything