After what has been a year with record rainfall, allergens such as mold spores are coming in very high across our region. To kill the mold spores we need a hard freeze and while our outer northern and western suburbs (Leesburg, Gainesville, Frederick, Germantown) have dropped close to the freezing mark, many of us have not had a hard freeze — characterized by four consecutive hours of temperatures below 32 degrees. A hard freeze is capable of killing the the mold spores and officially putting and end to the growing season.
A cold front will slide through our region on Sunday afternoon, ushering in much cooler temperatures and at least two opportunities for a hard freeze on both Wednesday and/or Thursday morning.
The image below (courtesy WxBell) shows the forecast low temperatures on Wednesday morning with many locations likely dropping to at or below freezing especially north and west of Washington.
Highs on Wednesday will struggle to reach 50 degrees in Washington with most locations holding in the middle to upper 40s. As high pressure begins to build across the area during the overnight hours, clear skies and calm winds will set up
perfect conditions for a widespread hard freeze across our region on Thursday morning. The image below (courtesy WxBell) shows temperatures even in Washington possibly dipping below 32 degrees for the first time this Fall with mid to upper 20s likely in the suburbs!