Sometimes the frontal boundary that separates air masses is very clearly defined, while other times that boundary is murky. Yesterday morning we saw an example of the former when a cool, dry air mass quickly displaced the muggy mess that had been over the area for a few days. Within a couple of hours the pressure jumped, a gusty northwesterly breeze kicked in, and the dew point fell by 20 degrees. Highs on Friday and Saturday were both above 90 degrees. The official observations in Central Park have reached 90 degrees on 21 days this year, one more than last year and the most since 2010.

Saturday was most likely the last 90-degree day of the year. The dry air mass overhead right now will bring us a seasonable and sunny day today, with the high right around the normal of 77. The wind will start coming out of the south tomorrow as the air mass moves out to sea, pushing our high up to 80 on Tuesday and maybe the upper 80s on Wednesday. There is a slight chance of showers or thunderstorms as the next cold front passes through town.

The mid-week front is expected to bring the coolest weather we've had in several months. Thursday's high will likely be in the mid 70s and the low Friday morning could dip below 60 for the first time since mid-June. The temperature and humidity are currently expected to increase as we head into the weekend with Sunday potentially being rainy as another cold front approaches.