How often does your city get single digit F (below -12 C) Temperatures (warmest, night)

[BMI]

My guess is about 20 days a year.
According to Environment Canada 1971-2000 data we average 32 days with lows below -10C (15F)

[irlinit]

Probably never here

[Qilin34]

They are now an unusual occurrence in the urbanised parts of Washington, DC (using KDCA as reference), but used to be far more common in the 1970s and 1980s, due to none other than UHI and a simple lack of monstrous cold. Since 1990, there have been only four months at KDCA with single digits: Jan 1994 (6 times), Feb 1996 (twice), and Jan 2004 and Jan 2009 each with one occurrence. Granted the first two of the months listed had Arctic outbreaks as notorious as the one impending one for the Midwest, and Jan 1994 is tied with Feb 1979 for the most single digit readings in a month since at least 1977, flaunting other notoriously cold months such as Jan 1977, Jan 1982, Dec 1983, Jan 1985, and Dec 1989.

Away from DC's UHI, at Dulles Airport (KIAD), since the turn of the century, they can be expected at most twice to thrice per winter, often isolated occurrences; they do not occur every year, however, with 2011/12 being a notable exception. I would caution making comparisons regarding the frequency of cold with pre-1990, due to the massive suburban development in western Fairfax and southeastern Loudoun counties (immediately adjacent to KIAD) since then. Low temp differences between KIAD and KDCA of at least 15 °F hardly, if ever, occur these days.

At Pittsburgh, almost always half a dozen (or more) times per winter. Don't know if there ever has been a year without single digits

[Adi from the Brunswicks]

Originally Posted by irlinit

Probably never here

Must have happened in London at least once in a couple decades from arctic blasts in spite of mild winters.

[chicagogeorge]

Average is 19, most single digits (-12C or lower) is 53 in a year at Midway Airport. On the other hand, west suburban Aurora average 28 such days.

[dunno what to put here]

Originally Posted by Adi from the Brunswicks

Must have happened in London at least once in a couple decades from arctic blasts in spite of mild winters.

fell to 3F at one of London's weather stations in 2010. That one station is much colder than the rest though.

[tarzan_taborda]

2 times in the last 82 years.

[Qilin34]

Originally Posted by Qilin34

They are now an unusual occurrence in the urbanised parts of Washington, DC (using KDCA as reference), but used to be far more common in the 1970s and 1980s, due to none other than UHI and a simple lack of monstrous cold. Since 1990, there have been only four months at KDCA with single digits: Jan 1994 (6 times), Feb 1996 (twice), and Jan 2004 and Jan 2009 each with one occurrence. Granted the first two of the months listed had Arctic outbreaks as notorious as the one impending one for the Midwest, and Jan 1994 is tied with Feb 1979 for the most single digit readings in a month since at least 1977, flaunting other notoriously cold months such as Jan 1977, Jan 1982, Dec 1983, Jan 1985, and Dec 1989.

I stand corrected...it fell to 7 F at KDCA on 6 Feb 1995, but then again that was the sole single digit reading that month

[Max96]

A couple weeks per year, probably, but it varies from year to year.

[Adi from the Brunswicks]

Originally Posted by Qilin34

I stand corrected...it fell to 7 F at KDCA on 6 Feb 1995, but then again that was the sole single digit reading that month

How about the last couple nights. No single digits. You will see it once again tomorrow night. Here it will.be a hi of 45 F and low of -3 F.