I would say yes, they need an enclosure especially if you want them to keep laying. My belief is that light and temp. effect the laying cycle. Hopefully others with more experience can add their 2 cents. 40 degrees isn't too extreme, even in an insullated coop with a heat light mine got that cold more than once through this harsh winter, but being outside unprotected you have to take into consideration wind which can make the actual temp. much colder!