New to old gardener-Straw bales?

[nltaff]

Got up this morning to find the temps hovering at 70! I immediately went out to sniff the blooming nicotiana all around the deck. So (per post above) the predicted high for tomorrow is only 65, and the low is 49?!? Just don't understand it, but I guess this is why.

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Last year, the tomatoes I planted in the asparagus garden (3 Black Krim) suddenly died overnight just about this same time (mid-late August). Never dreamed it was because of a chilly overnight temp. Anybody jump in here, do you think I should put that big plastic cover on now? I planned on re-installing it eventually, certainly by early Sept. or so. It does let in enough light for decent growth, it just means that I have to roll up the walls every morning, roll them down every (cold predicted) night.