December 2024 ended up with a mean of 6.8°C, that’s 1.9°C above the 1991-2020 LTALTA Long Term Average. This is usually defined as a 30 year period by the WMO., making it the joint 12th mildest since 1659.
Some places in England remained frost free.
December 2024 – CET Read More »
Not surprisingly, in this ever warming world of ours, the dates of the earliest and latest air frosts in Central England getting respectively later and earlier. The code behind that produced the scatter graphs below was a lot harder than I imagined. Along with the scatter graph and data grid, I also decided to add a smaller horizontal bar chart just to plot the annual distribution. The application is a lot more versatile than just finding the earliest and latest frosts and will come in useful in spotting other events in the daily CETCET Central England Temperature series.
As you can see from the linear trend in the graph below of minimum temperatures, the date of the latest air frostair frost An air frost occurs when the temperature of the air falls below 0.0°C in Central England is now closer to the 5th of April, much earlier than the 16th it was back in 1878.
The date of the first air frost is now 11 days later on the 13th of November, rather than the 2nd of November, as it was closer to back in 1878.
Dates of earliest and latest frosts in Central England Read More »
There’s been a steady decline in the number of air frosts occuring in Winter [DJFDJF Meteorological Winter comprising the months of December, January & February] across the UKUK The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. since 1960. In the southeast of England the decline in the last 64 years has been at the rate of 1.8 days per decade or 11.3 days. In the north of Scotland the decline has been somewhat slower at the rate of 1.4 days per decade or 8.6 days overall.
The climate record for air frosts only extends back to 1960 in the gridded form. I’m quite sure it could easily be extended back to at least 1884 by the UKMOUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy, but they obviously don’t seem to find the time or enthusiasm to get around to it. You would think that the work would be trivial, since they must already have gridded daily night time minimum data, perhaps they’re hoping for a crowd sourced group of volunteers to step in and do it for them.
Decline in air frosts in Winter since 1960 Read More »
The definition for frost severity as laid down by the Meteorological Office in their Glossary of 1991, has remained unchanged for many years. Frost severity is dependent not just on the lowest minimum temperature, but also on the wind speed, so there are two sets of values for ‘slight’, ‘moderate’, ‘severe’ and ‘very severe’, one for when mean wind speeds are 10 knots or more and one for when they are less.
There are many euphemisms for frost used by today’s weathercasters that are simply misleading and bad practice. Common amongst these are ‘sharp’, ‘touch’, ‘pinch’, ‘hard’, and ‘light’, they’re all bollocks as far as I am concerned. If weathercasters stuck to the same rigid definition the general public might have a better clue to just how severe an upcoming frost might be, what a forlorn hope of mine that will ever happen.
It’s also interesting to note that the glossary mentions just two basic types of frost, an ‘air frostair frost An air frost occurs when the temperature of the air falls below 0.0°C’, and a ‘ground frost’, so forget about ‘grass frost’, even if the thermometer that’s used to measure it is referred to as a ‘grass minimum’ thermometer.
Frost severity definition Read More »
The December 2023 cold spell Read More »
Did you know that a minimum air temperature of 0.0°C is NOT a frost? An air frostair frost An air frost occurs when the temperature of the air falls below 0.0°C only occurs when the air temperature in a Stevenson screen falls below zero celsius i.e. goes negative and not before. The Met OfficeUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy website in an item about the types of frost is wrong. I did inform them of the fact and they have promised to correct it.
The UKMOUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy are in pretty good company not understanding what the exact definition of frost is, neither do the “experts” down at the Royal Meteorological Society either. I informed them about this slip up on their website a while ago, but so far the haven’t bothered to reply.
I notice that the Royal Meteorological Society have now corrected the ‘Touch of frost’ article on their website about the definition of what an air frost is, but not so much as a thank you from them. At least I did get a reply from the Met Office help desk, but it still hasn’t been corrected on their website the last time I looked.
I was astounded to find when I bought the book by the Met Office called ‘Very British Weather’ to add to my collection of books on weather and climate, that they had it wrong too.
On page 181 of the book I notice it states that ‘freezing conditions’ occur ‘when the temperature is at or below 0°C’. There’s no arguing that 0.0°C is the freezing point of water, but ‘freezing conditions’, even an ‘air frost’, surely can’t occur until the air temperature is below that temperature, and not at it. It’s a small even a trivial point, but these three instances are or were all wrong. I’m still trying to understand what the paragraph at the foot of the page is trying to say.😉
The definition of freezing and what constitutes an air frost Read More »
A map of air frosts, ground frosts and ice days in the meteorological winter of 2022-23. Remarkably there were more air frosts at Benson in Oxfordshire than there were at Aviemore in the Highlands. I should make an effort to compare these results with a 30 year average but I don’t have the time to compile the stats for each station at the moment. Don’t forget to click an image to enlarge it. Here for completeness is the thermograph for Benson to prove just what a cold hole it is.
Winter [DJF] 2022-23 Frost Read More »
Dear Diary
Another very cold day across all parts of IONAIONA Islands Of North Atlantic.
Yes I know there's an island called Iona, but this is so I don't have to use the term 'British Isles' when referring to the whole of Ireland and the UK. this Sunday, exceptionally so across parts of the south with anomalies as low as -10°C this lunchtime, as this cold spell continues. Many areas will see an ice day today with temperatures remaining sub-zero this afternoon. Finally, the northern Highlands of Scotland, have lost that persistent and tenacious east northeast wind of the last week that has been funneling a feed of milder winds into the Moray Firth. No doubt it’s just taking a breather and will be back later in the week.
A distinctly nippy IONA Read More »
Dear Diary,
Carol Kirkwood reckons that “We’ve got a widespread frost”. Not really Carol that’s not a widespread frost, if you look at a chart of the 18-06 minimum temperatures this morning (an air) frost has occurred in places where high ground has given shelter from the wind and helped to keep skies clear of cloud across southern Scotland, and parts of western England. We may have a widespread frost later in the week by the looks of it. I would agree that there may have been a widespread ground frost, but that wasn’t what she was talking about.
We’ve got a widespread frost Read More »
Dear Diary,
The days of air frostair frost An air frost occurs when the temperature of the air falls below 0.0°C and ground frost were well down on their respective LTALTA Long Term Average. This is usually defined as a 30 year period by the WMO. for all regions, thanks to the very mild weather. I would have like to have added a colour contoured map but the Met OfficeUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy don’t seem to generate them anymore for frost. Still plenty of sites still to report their first frost, some of them inland as well. My SYNOPSYNOP SYNOP (surface synoptic observations) is a numerical code (called FM-12 by WMO) used for reporting weather observations made by manned and automated weather stations. SYNOP reports are typically mad hourly and consist of groups of numbers (and slashes where data is not available) describing general weather information, such as the temperature, barometric pressure and visibility at a weather station. records are never guaranteed to be 100% complete, so I may have missed the odd one because either the value or the whole observation at 06 UTCUTC Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used prime meridian) and is not adjusted for daylight saving time. It is effectively a successor to Greenwich Mean Time (GMT). was missing. I could now, at least for the UKUK The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. that is, generate totals from the 21-09 UTC extremes now that they are finally being included.
Autumn 2022 [SON] – Days of Frost Read More »
Dear Diary,
Temperatures are only just going to manage to get up above freezing for a short while across the Highlands this afternoon. The air temperature at Aviemore was -1.2°C at 1100 UTCUTC Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used prime meridian) and is not adjusted for daylight saving time. It is effectively a successor to Greenwich Mean Time (GMT)., and here in StrathpefferStrathpeffer Strathpeffer (Scottish Gaelic: Srath Pheofhair) is a village and spa town in Easter Ross, Highland, Scotland, with a population of 1,469. it’s just 2.2°C at 1215 UTC. Just caught the latest forecast from the BBCBBC The British Broadcasting Corporation (BBC) is the national broadcaster of the United Kingdom, based at Broadcasting House in London. It is the world's oldest national broadcaster, and the largest broadcaster in the world by number of employees, employing over 22,000 staff in total, of whom approximately 19,000 are in public-sector broadcasting. on the News Channel. SKLSKL Sarah Keith-Lucas an English meteorologist and BBC weather presenter reckons that it won’t be quite as cold as last night with only a patchy frost overnight particular across Scotland, and then goes onto show this rather contradictory graphic of temperatures at 06 UTC, with labels of temperature that bare no relation to the NWPNWP Numerical weather prediction uses mathematical models of the atmosphere and oceans to predict the weather based on current weather conditions. blue contoured data that they overlay on the chart which also seems to be missing a few labels as well.
With a maximum of 2°C so far today I would make an educated guess that we’ll see a widespread moderate frost across the Highlands overnight and not at all patchy.
Contradictory temperature charts Read More »
As Greavsie once said “It’s a funny old game Saint” and the same is true of weather as it is of football. We had to wait all Autumn till Sunday night before we saw our first air frostair frost An air frost occurs when the temperature of the air falls below 0.0°C, and now we’re looking at getting four frosts in a row here in StrathpefferStrathpeffer Strathpeffer (Scottish Gaelic: Srath Pheofhair) is a village and spa town in Easter Ross, Highland, Scotland, with a population of 1,469.. It’s just the luck of the draw with the timing of these frontal systems this week being early morning rather than in the early hours I suppose. Three cold days in the Highlands. The mean temperature in my AWSAWS Automatic Weather Station on Monday [00-00] was just -0.6°C. Temperatures never exceeded 5.2°C today and they are already falling as skies clear late this afternoon. Here’s hoping for a frost tonight anyway!
It’s a funny old game Read More »
The overnight fog has been persistent across the Cromarty Firth and Straths and glens of Easter Ross this morning. In fact temperatures are still subzero after a moderate overnight frost. Here in StrathpefferStrathpeffer Strathpeffer (Scottish Gaelic: Srath Pheofhair) is a village and spa town in Easter Ross, Highland, Scotland, with a population of 1,469. temperatures fell to -3.5°C in the first frost of the Autumn. The fog looks to be around 300 feet thick or so and is blowing up the strath from the east. Higher up above the inversion at around 750 feet there’s a 5 to 10 knots wind blowing from the south. So as well as fog blowing up the strath from the east some is blowing up and over the ridge of the Cat’s back from the south. You can barely see what all the fuss is about in the lunchtime satellite image.
Fog persists across Easter Ross Read More »
So far Autumn 2022 has been relatively frost free across IONAIONA Islands Of North Atlantic. Yes I know there's an island called Iona, but this is so I don't have to use the term 'British Isles' when referring to the whole of Ireland and the UK.. It’s now the 19th of November, and although we’ve dropped down to 0.0°C here in StrathpefferStrathpeffer Strathpeffer (Scottish Gaelic: Srath Pheofhair) is a village and spa town in Easter Ross, Highland, Scotland, with a population of 1,469., like in many other places, we still await the first air frostair frost An air frost occurs when the temperature of the air falls below 0.0°C of the season.
Frost free Autumn for many Read More »
