Heavy rains

Heavy rains pass through Cockeysville along York road Tuesday afternoon. Cars make their way through the large pools of water along York Road. (Lloyd Fox / The Baltimore Sun / September 19, 2012)

A front of cold, Canadian air helped spawn Tuesday's storms, and it also means a stretch of dry, cool air ahead. While some storm chances appear again this weekend, overnight lows are plunging.

As the storms passed through Tuesday afternoon, BWI Marshall Airport dropped 11 degrees in two hours, from 79 to 68. The overnight low fell to 60, which could actually be one of the warmest nights over the next week or so.

Tonight, lows are expected in the mid-50s, with highs in the low- to mid-70s both Wednesday and Thursday. Daytime humidity levels are expected to stay below 40 percent relative humidity both days.

Isolated storms in the forecast for Saturday could make things slightly warmer and more moist again, with highs around 80 Friday and Saturday, the first day of fall. Lows will remain around 60 before plunging toward the 40s Sunday and Monday nights. The forecast is calling for 51 degrees both nights, at the moment.

Baltimore hasn't seen a temperature that low since May 20, and it hasn't seen the 40s since the day before that, May 19.

Have a weather question? E-mail me at sdance@baltsun.com or tweet to @MdWeather.