Winter Field Day is presented by the Winter Field Day Association (WFDA), “a dedicated group of Amateur Radio Operators who believe that emergency communications in a winter environment is just as important as the preparations and practice that is done each summer but with some additional unique operational concerns.”
The Association's website describes the objective of Winter Field Day as follow:
We believe as do those entities of ARRL Organizations like ARES & RACES that maintaining your operational skills should not be limited to fair weather scenarios. The addition of Winter Field Day will enhance those already important skills of those that who generously volunteer their time and equipment to these organizations. This is why WFD is open to all licensed amateur radio operators worldwide.
Disasters are unpredictable by nature and can strike when you least expect them. WFDA's goal is to help enhance your skills and ready you for all environmental conditions found in the US and Canada during the spring, summer, fall and winter Preparedness is the key to a professional and timely response during any event and this is what local and state authorities are expecting when they reach out to the emergency service groups that offer their services.
If you are serious about emergency communications as we are; we welcome you to join us for our yearly event. We are sure you will find this event a pleasant change and challenge to that of a normal summer time field day.”
The following information is courtesy of the WFDA's website but please visit it for complete rules and information.
Purpose: To foster Ham camaraderie, field operation, emergency operating preparedness, and just plain on the air, outdoor fun in the midst of winter for American, Canadian and DX Amateurs.
When: Winter Field Day runs for 24 hours during the last full weekend in January each year from 1900 UTC (2pm EST) Saturday to 1900 UTC (2pm EST) Sunday. For 2018, the dates are January 27 and 28. Station setup may commence no earlier than 1900 UTC (2pm EST) on Friday, January 26. Station setup may consume no more than 12 hours total. How and when you schedule/spend those 12 hours is up to you.
Bands: All Amateur bands, HF, VHF and UHF except 12, 17, 30 and 60 metres.
Modes: Any mode: CW, SSB, AM, FM, D-Star, C4FM, DMR, Packet, PSK, SSTV, RTTY, Olivia, Satellite, etc.
Suggested Frequencies: (to make it easier for entrants to find each other) HF CW – 1810-1820, 3.530-3.550, 7.030-7.050, 14.035-14.055, 21.030-21.050, 28.030-28.040
HF SSB – lowest 30 kHz of the US General Class Phone bands (160m- 15m), 28.400-28.425MHz (10m) 6m/VHF/UHF – adjacent to, but not on, nationally recognized simplex calling channels.