After a warm stretch for the Bay State that saw temperatures climb into the 50s, a new weather system is set to pull temperatures below normal beginning Friday night. Already, temperatures are expected to fall about five to 10 degrees on Friday, with highs of 39, 35 and 37 projected in Boston, Worcester and Springfield, respectively. Those relatively normal temperatures are set to give way to a stretch of much colder weather, with projected highs in the low 30s and high 20s.