Colder this week, some wintry/snow showers, widespread frost and ice.

Car fully thawed in the sun today in cork city, frozen again now already.

That is one major difference between this cold spell and other ones we get. It's winter, the sun doesn't last long, so the "max" temps are, in general, around for a lot less time then the min temps allowing more ice to form versus our usual cold spells in say March.

Precipitation for next 24 hours

Potentially Eastern areas have a better chance tomorrow evening

19.44

Scattered showers tonight in Connacht and Ulster, some turning to sleet and snow later especially over high ground. Towards dawn, the wintry showers will extend further south.

Tomorrow

An icy start on Thursday with black ice and patches of freezing fog in places leading to hazardous travel conditions. There will be well scattered showers of sleet or snow in the morning, with little accumulations. Sunny spells will follow with wintry showers becoming confined to northern coastal counties during the afternoon, potentially also affecting some eastern areas tomorrow evening.

We don't usually get cold frosty weather until January onwards, December is more often than not mild.

November was much more bizarre weather wise, this is cold and early cold but it is not that abnormal.

The overall blocking pattern is more unusual than the temperatures. We haven't seen a -NAO like this in December since 2010, thus why a good few comparisons with that year despite it being misleading to the average Joe who doesn't give a toss to know what the North Atlantic Oscillation is or what relevance it means to us. Nonetheless, it is of interest to long-term weather observers like myself and others who are fascinated by this stuff.

The temperatures aren't that "overly" unusual meanwhile in comparison though certainly not an every winter case like some make out. If we didn't have such a modified atmosphere from all the warmth, I'd say this pattern would have been severe. However, low solar, long nights and slack flow will certainly help in plunging the air temperature values.

Rather than making assumptions without evidence, here's a statistical look at how unusual the temperature values are relative for the month of December.

A minimum temperature of at least -5C somewhere in Ireland happens on average every 2-3 years in the month of December. This has been achieved in 2020, 2017, 2016, 2014, 2012, 2010, 2009, 2008, 2007, 2005, 2003, 2002 and 2001 this century to date. With 62% of the years achieving it, it's clear this is rather common. However, the problem of using this quantifying method is that all it takes is one common frost hollow or notorious station for low minimum temps to achieve the value without considering regional variation where such a value will be much more common or rare for others. To counter this, I have made the below table from the same selection of stations used to calculate the Irish mean temperature (IMT) for the forecast contests minus Oak Park which has missing data from 1997-2003 and the likely return period based on available data for each temperature threshold at that station giving a reasonable estimate of how unusual it is.

Results on the whole are very similar across the four stations. Typically expect to see the following return periods for each threshold.

<-4C being every 2 years, <-5C being every 4 years, <-6C being every 6 years, <-7C being every 9 years and <-8C being every 13 years. Therefore, from this simple analysis we can say that -4C and even -5C to an extent are not that unusual to see in Ireland in December, at least at these stations. Coastal parts would be far more uncommon. Meanwhile -6C or lower can be once or twice a decade whilst -7C or lower can be anticipated once a decade and a half on average. This analysis doesn't take into account the count of days with threshold achieved in a December however - there were many nights for instance in December 2010 below -8C and even -10C wasn't all that uncommon in the frost hollows.

This analysis will probably blend away into the chit-chat but I wanted to see truly how "unusual" these temperature values are in the month of December in Ireland with statistical evidence rather than assumption.

Thank you for reading.

Super info!!

Apart from 09/10 I don't remember December cold pre Christmas in 50 years. Its that unusual!

Well yes that is more unusual, the analysis didn't take into account what point of December the values occurred, it was for any part of the month. Another two significant years to add to your list - 1950 and 1981. Also 1878, 1879 and 1916 from a long time ago, I remember them well 😂

Ice days, with or without freezing fog.

It is extremely unusual in Ireland for daytime temps to remain below freezing. The warning is for people moving about, who may encounter ice at any hour of the day on the roads and footpaths over the next few days, or those who are keeping livestock where the risk of feed and water pipework freezing is high.

If you think your smartarsery makes you sound either more knowledgeable that Met É, or somehow edgy, it really doesn't.

Surprised there's not more talk about tomorrow afternoon for Dublin area?

Clearly an area of ppn clips the coast!

Coincides with a bubble of colder air!

From past experience if you dont want chat and clutter - move to the Technical <120hrs thread - because there'll be lots of both on here.

But thats just incorrect. If we were staying below zero for extended period id understand the hype.

We are barely getting below zero at night at the moment.

Its a non event. Cold yes. But not as surprising as the 17 degrees on the 11th / 12th of november. Did we have a thread for that?

I think you have made your point at this stage Gusser09 no?