National Weather Service United States Department of Commerce

Fire Weather Concerns Continue in California; Pattern Change Possible Later this Week

Low humidity and gusty winds will continue across portions of California through Monday, although the weather pattern may change by Wednesday with increasing rain chances. Elsewhere, chilly conditions will persist across the northern and eastern states with rounds of light snow over the Great Lakes and Northeast, while areas of rain develop in south Texas and the Gulf Coast. Read More >

   Winter Weather   

Winter Weather Products

Local Products

Winter Products from National Centers


Watch/Warning/Advisory Terminology & Criteria

  • Warnings:
    A warning is issued to alert the public to imminent dangerous winter weather. Normally a warning is issued after a winter storm watch has been in effect. A winter storm watch may not precede a warning if winter weather develops quickly and unexpectedly. A Winter Storm Warning is issued when heavy snow, significant freezing rain, or heavy sleet is expected to occur. Usually issued 6 to 18 hours in advance of the winter weather. A Blizzard Warning is issued when sustained or gusty winds of 35 mph or more are expected to reduce visibility at or below a quarter of a mile due to falling and/or blowing snow for at least three hours. Wind Chill Warnings are issued when wind chills are expected to be below -24 degrees fahrenheit.
  • Watches:
    A watch is issued to alert the public to the potential for dangerous winter weather. A Winter Storm Watch is issued when conditions exist for the possible occurrence of dangerous winter weather such as a blizzard, heavy snow, significant freezing rain or heavy sleet. Usually issued 12 to 36 hours in advance of the winter weather.
  • Advisories:
    A less severe winter weather event will prompt the issuance of an advisory. An advisory is named specific to the weather event expected and is issued when the event is expected to be widespread. Travel by foot or vehicle may be dangerous during an advisory even if the winter weather is not expected to reach winter storm criteria.
Criteria Maps of Winter Storm Watches, Warnings & Advisories for New Jersey, eastern Pennsylvania, Delaware, eastern Maryland
12-Hour Advisory Snowfall
12-Hour Warning Snowfall
24-Hour Warning Snowfall
Freezing Rain Advisory
Ice Storm Warning
Wind Chill Advisory
Wind Chill Warning

Gradient high wind outlooks, watches, warnings, and wind advisories shall be issued using the following wind speed values
Product Type Sustained Wind ( 1 Hr) Any duration gust
High Wind Outlook >= 40 MPH (35 KTS) >= 58 MPH (50 KTS)
High Wind Watch >= 40 MPH (35 KTS) >= 58 MPH (50 KTS)
High Wind Warning >= 40 MPH (35 KTS) >= 58 MPH (50 KTS)
Wind Advisory (land) 31-39 MPH (27-34 KTS) 46-57 MPH (40-49 KTS)
Wind Advisory for area lakes 25-30 MPH (22-26 KTS) 40-45 MPH (35-39 KTS)



Snowfall from Past Winters

Seasonal Snowfall Totals from 1979-Present (updated May 2017):


Preliminary Top Ten Philadelphia Snow Storms (updated May 2017):










January 7-8 1996





February 5-6 2010





December 19-20 2009




January 22-23 2016





February 11-12 1983





December 25-26 1909




April 3-4 1915





February 12-14 1899





February 15-18 2003





January 22-24 1935




Winter Weather Awareness and Safety