A large arctic high pressure system moved toward the area during the 16th and 17th. The extent of the arctic air mass kept maximum temperatures only in the teens and 20s, with minimum temperatures down into the single digits. As a storm system remained well to the northeast, the combination of this along with strong arctic high pressure to the west allowed for gusty winds. This produced wind chill values around zero for awhile, especially during the nighttime hours. The morning of the 17th was the coldest morning in several years. For example, the New Castle County Airport bottomed out at 5 degrees. This was the coldest morning since January 28, 2005 when the low temperature bottomed out at 1 degree.
Some specific low temperatures on the morning of the 16th included; 7 degrees at Redden (Sussex County), 10 degrees in Greenwood (Sussex County), 11 degrees at the New Castle County Airport in Wilmington (New Castle County), 12 degrees in Blackbird (New Castle County), 13 degrees at both the Dover Air Force Base (Kent County) and the Georgetown Airport (Sussex County). The wind chills dropped into the single digits during the night of the 15th, however then lowered to between zero and five below zero at most locations on the 16th. These bitterly cold wind chills prevailed through the entire day on the 16th.
Some specific low temperatures on the morning of the 17th included; 0 degrees at Blackbird (New Castle County), 0 degrees at Redden (Sussex County), 3 degrees at Greenwood (Sussex County), 5 degrees at the New Castle County Airport in Wilmington (New Castle County), 5 degrees at the Georgetown Airport (Sussex County), and 6 degrees at the Dover Air Force Base (Kent County). The wind chills dropped to between 2 below zero and 5 above zero during the early evening hours of the 17th. The wind chill values were as low as 5 degrees below zero during the morning hours of the 17th.

Cold/Wind Chill in INLAND SUSSEX, DELAWARE
From 16-JAN-09 00:00:00 to 18-JAN-09 09:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The temperature bottomed out at 13 degrees during the early morning of the 16th at the Georgetown airport. At this same location, the temperature bottomed out at 5 degrees during the early morning of the 17th. Some mesonet sites had low temperature readings down to zero, especially on the morning of the 17th. These bitterly cold air temperatures combined with some wind, which produced wind chill values to zero or just below for a time.

Cold/Wind Chill in NEW CASTLE, DELAWARE
From 16-JAN-09 00:00:00 to 18-JAN-09 09:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The temperature bottomed out at 11 degrees during the early morning of the 16th at the New Castle County Airport in Wilmington. At this same location, the temperature bottomed out at 5 degrees during the early morning of the 17th. Some mesonet sites had very similar low temperature readings and the wind added in produced wind chill values to zero or just below for a time.

Cold/Wind Chill in KENT, DELAWARE
From 16-JAN-09 00:00:00 to 18-JAN-09 09:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The temperature bottomed out at 13 degrees during the early morning of the 16th at Dover Air Force Base. At this same location, the temperature bottomed out at 6 degrees during the early morning of the 17th. Some mesonet sites had low temperature readings down to zero, especially on the morning of the 17th. These bitterly cold air temperatures combined with some wind, which produced wind chill values to zero or just below for a time.