To me, it all depends on how deep the layer of mulch is. If it is more than two inches I would think it would act like a thermal blanket and NOT let the sun warm the soil. How cold it gets at night doesn't matter if things get to warm up as soon as the sun starts shining. It also depends on what you are sowing - some things like cool damp soil while others require sunshine to sprout.

It has become pretty thin in many areas from breaking down and/or blowing off. It is maybe 2-3 inches thick in other areas. Will it harm the stuff already poking above ground if I take it off right before a 38-degree night? Instinct says it is a bad idea, but on the other hand....it has been warm overall lately. Besides, mulch is more of a protection against heaving, right? I assume there is little danger of that right now. I just do not want to hurt anything that has not poked above the mulch yet but will be exposed if I remove it too early.

(If anyone has ever watched Tangled and seen Rapunzel arguing with herself, that is me! Lol)

What I've done before is to remove by hand as much mulch as I can without removing it around the newly sprouted plants. It ends up looking silly with little skirts of mulch around the green stalks but newly sprouted stalks are so fragile I just didn't want to risk it. Most of the spring sprouting plants in my garden are cold weather plants that can handle it down to 30 or even 28. Most of the more delicate things that hate cold weather don't even emerge until late May or early June - if they were up and growing now I would be worried, but they are not.

Good point...thanks! I ended up removing most of it. I am glad I did, as stuff is already sprouting.

And....everything did just fine with the mulch removal, it seems. Yay!