This is going to be the first weather update for Halloween 2018. This is meant to be just for fun and for the interest of weather enthusiasts as Halloween, which is October 31, is 30 days away. I’m going to briefly look at previous Halloweens of the 21st century and then show what some long range models are suggesting for Halloween and the end of October.

Previous Halloweens

Many of the recent Halloweens the UK has experienced in recent times have been unusually warm (See image); 2014 recorded the highest Halloween temperature on record in the UK with 23.6°C. The table in the image linked above shows the highest temperature recorded in the UK for every Halloween from 2000 to 2017. As you can see, 2014 was the warmest (dominated by long fetched, warm southwesterly winds) whilst 2008 was the coldest (dominated by cold northeasterly winds) in terms of absolute maximum temperature for the UK.

500mb height chart for Halloween 2014, 31 October 2014.
500mb height chart for Halloween 2008, 31 October 2008.

Long range model outlook for Halloween

The CFSv2 long range model, from its 12 o’clock run on 30th September, below shows a blocking area of high pressure just to the northeast of the UK bringing winds in from an easterly direction. The upper air temperature chart shows there is some cold air entrenched within this high pressure meaning it’d be chilly with daytime temperatures struggling for many in the single figures ending on frost overnight. There’d be some patches of fog and mist possible. Just a cold and dry day all in all this particular CFSv2 run suggests for Halloween 2018. This will change on other runs of the model though so I can’t emphasise enough that this is just for fun.

The chart below is the 500mb height anomaly prediction by the Beijing Climate Centre (BCC) long range model for 31 October to 9 November 2018. It shows an area of above average heights over the north Atlantic and to the northwest of the UK with below average heights over Iberia. The mean wind would be a northeasterly direction in this setup and by the end of October, northeasterlies would be very cold with the chances of snow increasing.

Summary

Quite an interesting start to the Metcast Halloween updates with both the BCC and CFSv2 models hinting at some cold weather around Halloween 2018. At this point of time though, this isn’t to be taken seriously at all. The updates will get more serious once we get to around the 23 or 24 October. Stay tuned!

Sean Bruen is a forecaster for Metcast (and Snow Watch). His main interests are historical and long range weather. He LOVES snow (his Twitter account is @SnowbieWx, go figure!) and his favourite season is Winter.