Yowza. I hate when that happens.
Yes they will definitely need to be protected. At seedling/young plant stage, Tomatoes can handle lower temps better than peppers but will begin to shut down — yellow and purple — after about 3 days/nights in the 40’s. Daytime high of 65+ will help them recover. So cover just before sundown to keep in daytime warmth, then uncover in the morning as soon as sunlight reaches the plants to warm them up.
Peppers suffer both from low air temp and low soil temp. You may want to provide temporary black plastic soil cover/mulch — trash bag will do. Then cover the plants.
Think in terms of your own sensation — multiple layers create insulating warmth. Something porous inside, solid outside. Tight cover prevents loss of warm air and drafts. But it’s AS critical to UNcover in the daytime, both if clear covers are used to prevent overheating, and if solid/opaque covers are used to for sunlight.
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