January Temp Departure: Record-Breaking Cold?

[Maximum lawman]

If you estimate the mean daily temp departure from observed data and the current forecast through the end of January, KPHL could easily see a departure of -5.5 for the month. I looked around some, and can't find any climate record data for monthly temperature departures. Curious if someone has the data for biggest positive and negative monthly departure. For a reporting station that has few recent negative departures at all, that's pretty remarkable.

[BucksCO_PA]

If you estimate the mean daily temp departure from observed data and the current forecast through the end of January, KPHL could easily see a departure of -5.5 for the month. I looked around some, and can't find any climate record data for monthly temperature departures. Curious if someone has the data for biggest positive and negative monthly departure. For a reporting station that has few recent negative departures at all, that's pretty remarkable.

 

That's what makes JAN 1977 so impressive, PHL ave for the month was 20.0, at least -10 for the month based on the 30yr "normal" at that time. JAN 1977 is a full 4 degrees colder than the 2nd coldest JAN on record at Philly.

 

JAN 2004 was -6.2 at PHL

[JCT777]

I'm being lazy by not digging up this info myself, but if we are considering any month (not just January) - I'd have to think December 1989 is pretty high on the list of biggest negative monthly temp departures.  I'm sure it wasn't as big of a negative departure as Jan 1977, but I remember it being very very cold.

[Maximum lawman]

Cool, interesting, thanks. I'm new to the area so i don't have the climatological history. But, to give this perspective, this cold departure equates to a July with an average temp of 85, which probably equates to an average high of 93 and low of 77, which would be ridiculous for an entire month.

[NJ_Ken]

I'm being lazy by not digging up this info myself, but if we are considering any month (not just January) - I'd have to think December 1989 is pretty high on the list of biggest negative monthly temp departures.  I'm sure it wasn't as big of a negative departure as Jan 1977, but I remember it being very very cold.

 

I am being similarly lazy, but I suspect that February '79 is right up there, too.  The only thing that might hurt that month is the fact that the last week of the month of kind of normalish.  The first three weeks of February 79 were insane in terms of overall cold without even comparing to norms, which are steadily warming throughout the month.  February 79 (at PHL) had two days with lows below 0 F with another at 0 F and another of 1 F and three MORE days with lows of 2 F.  That is 6 days with lows of 2 F or below in the space of 3 weeks in February!  That month also featured 8 days where highs did not get out of the teens, and we've learned these past few weeks just how hard that is to do in January, let alone February.  Look at the high/low (F) for this 11-day stretch starting February 9, 1979:  19/8, 18/-1, 14/-2, 16/2, 15/5, 14/2, 23/12, 24/8, 13/2, 14/0, 30/12!!! 

 

Heck, if I am going to look up the dailies, I might as well see how the month fared overall.  Average temperature in Feburary 1979 was 23 F, which was 11.8 F below average.... shockingly, that was NOT the coldest February in Philadelphia history.  1934 averaged 22.2 F, which was 12.6 F below average (but remember 1934 pre-dates PHL as a official reporting location for Philadelphia).  It appears, though, based on departures, both of those months were "colder" than January 1977.     

[RedSky]

That's what makes JAN 1977 so impressive, PHL ave for the month was 20.0, at least -10 for the month based on the 30yr "normal" at that time. JAN 1977 is a full 4 degrees colder than the 2nd coldest JAN on record at Philly.

 

JAN 2004 was -6.2 at PHL

Been many references to this being the coldest weather since 1994 but january 2004 has mostly been ignored

[KamuSnow]

I am being similarly lazy, but I suspect that February '79 is right up there, too.  The only thing that might hurt that month is the fact that the last week of the month of kind of normalish.  The first three weeks of February 79 were insane in terms of overall cold without even comparing to norms, which are steadily warming throughout the month.  February 79 (at PHL) had two days with lows below 0 F with another at 0 F and another of 1 F and three MORE days with lows of 2 F.  That is 6 days with lows of 2 F or below in the space of 3 weeks in February!  That month also featured 8 days where highs did not get out of the teens, and we've learned these past few weeks just how hard that is to do in January, let alone February.  Look at the high/low (F) for this 11-day stretch starting February 9, 1979:  19/8, 18/-1, 14/-2, 16/2, 15/5, 14/2, 23/12, 24/8, 13/2, 14/0, 30/12!!! 

 

Heck, if I am going to look up the dailies, I might as well see how the month fared overall.  Average temperature in Feburary 1979 was 23 F, which was 11.8 F below average.... shockingly, that was NOT the coldest February in Philadelphia history.  1934 averaged 22.2 F, which was 12.6 F below average (but remember 1934 pre-dates PHL as a official reporting location for Philadelphia).  It appears, though, based on departures, both of those months were "colder" than January 1977.     

 

Speaking of 1979, that February was indeed cold, but not much snow until the PD storm, after which it milded up pretty good, as you mentioned. Looking at our current cold spell, in contrast with that one, and actual temperatures aside, I think I'd rather have the snow on the front end than the back end, if we had to choose.

[famartin]

Here's a list of the coldest January's at PHL:

 

1977 20.0

1918 24.1

1893 24.1

1970 24.5

1982 24.7

1945 24.8

1961 25.0

1875 25.2

1981 25.3

1940 25.3

1912 25.4

1948 25.9

1904 25.9

2004 26.1

1984 26.2

1920 26.8

1881 26.8

1988 27.3

1985 27.3

1994 27.4

1963 27.4

1971 27.8

1888 27.8

1978 28.0

1877 28.0

2003 28.5

1976 28.7

1968 28.8

2009 29.0

1966 29.0

1965 29.1

1957 29.2

2011 29.3

1886 29.3

1879 29.3  

[mgerb]

Cool, interesting, thanks. I'm new to the area so i don't have the climatological history. But, to give this perspective, this cold departure equates to a July with an average temp of 85, which probably equates to an average high of 93 and low of 77, which would be ridiculous for an entire month.

 

The degree of variance in monthly temperatures during cold-season months is much higher than summer months. Thus, a 5 degree departure in summer is very impressive, while during a winter month like January, the same departure is not as unusual.