The autumnal equinox, just before 11 a.m. today, marks the astronomical start of the fall season. The sun’s direct rays, which have been in the northern hemisphere during the spring and summer, pass back over the equator for the equinox. The amount of daylight and darkness is roughly equal throughout parts of the world. The sun’s direct rays will then travel into the southern hemisphere as we get closer to winter.
Although today will be warm and humid with highs in the 80s, a cold front will pass through the area tonight. Cooler air will spill back into the region Sunday into Monday. As high pressure builds into the area Monday into Tuesday, some of the coolest temperatures since mid-May will occur on Tuesday morning. Lows in the metro will drop into the mid & upper 40s, with lows near 40° well northwest of the metro. A few isolated upper 30s are possible in the mountains.