Spring

It has been an exceptionally warm spring, with temps in the 80"s.  I planted spinach, lettuce, turnips and chard in the garden, so far only the lettuce is germinated, is it possible that the soil temp is too high?

I've started more lettuce, chard, cabbage, cauliflower, tomatoes, peppers, and kale, in seed trays under lights in the garage.  The electric heat mat seems hotter than usual this year, and some of the peppers are not up after two weeks, although the tomato seed I saved sprouted just fine in the same tray. Possibly bad seed?