A cold March?

[Greg Gruner]

Today's outlook from the Met Office:

"UK Outlook for Sunday 6 Mar 2016 to Sunday 20 Mar 2016:
On the whole, cold and changeable conditions look to dominate through the period. Spells of wet and windy weather are likely as frontal systems push in from the Atlantic, but there should also be periods of more settled, crisp and bright conditions in-between. There will be some sleet or snow at times, either from showers in the colder outbreaks or due to frontal systems running into cold air. Temperatures will generally be below average, with widespread overnight frosts likely."

They have certainly gone unequivocally for a cold spell ("below average"). Not sure what this is based on, but presumably there are indications that the jet stream will be to the south of the UK for most of March.

We have had a very mild December (+6.0 compared to average at Farnborough), a reasonably mild January (+1.0 at Farnborough) and February so far is +0.7 at Farnborough. As March is climatologically 2.3C warmer than February, the likelihood is that if March has an anomaly of -2C or colder, it will be the coldest month of the "winter season" (though of course it is not a winter month). I'm not sure how often this has occurred (2013 came close, but February was still slightly colder than March that year).

[Len Wood]

March 2013 was certainly a cold one with an average of 5.39°C at Plymouth.

Looking at the long term Plymouth record 1874-2015 though, it was only 11th equal coldest.
Here are the 19 coldest which were one standard deviation or more below the long term average:

1883 4.15
1892 4.35
1962 4.50
1888 4.65
1900 4.83
1955 4.83
1887 5.00
1916 5.00
1901 5.22
1886 5.25
1898 5.39
1909 5.39
2013 5.39
1891 5.45
1958 5.56
1970 5.60
1937 5.61
1917 5.67
1889 5.85
........

[Len Wood]

The Met Office are certainly expecting a cold spell due to Sudden Stratospheric Warming.

See their blog:

http://blog.metoffice.gov.uk/

[Nicholas Gardner]

The mean temperature for the first half of March has indeed been colder than monthly average but then you would expect that as the second half normally warms up.

Then again, it has been the consistently cool/cold nights rather than the days that have brought the average temperature down.

I suspect (given the forecast) that this March may well end up around average or even slightly above.

March 1st - 16th:
Mean minimum = 1.7°C (-2.5°C)
Mean maximum = 11.2°C (0.0°C)
Mean = 6.5°C (-1.3°C)
Rain = 39.2 mm (of which 22 mm fell on the 9th)
Sunshine = 80 hours.

Sunshine struggled for the first week but it has been mainly sunny since. It needs to carry on being sunny to fall in-line with recent Marches that have seen sunshine totals toward the 200 hours mark.

[Len Wood]

March 1st-16th

Mean max 11.1°C
Mean min 3.5°C

Last year for same period:

Mean max 10.2°C
mean min 4.5°C.

So it has been warmer by day but cooler by night this March.

[Greg Gruner]

For Farnborough, March 1-18:

Mean max 9.3C
Mean min 0.8C
Mean 5.1C (estimated -1.7C compared to the LTA).

I think it will a close thing as to whether March makes it as the coldest month of the winter period. The February mean (the next coldest month) was 5.3C. It does look like the weather may get slightly milder approaching Easter, but the charts show a possible northerly after Easter to finish off the month. I don't know how often it has happened that March has been the coldest month. Does anyone have any information on this?

[Len Wood]

I have looked at the Plymouth record going back to 1874 and I counted 10 years when March was colder than the winter Dec, Jan, Feb months.

2013
1962
1958
1937
1925
1922
1916
1898
1892
1883

They have become rare in the last 50 years.

[Nicholas Gardner]

Well in the end this March did end up colder than my estimated LTA but it was the nights that were consistently cold whereas the mean maximum temperatures ended up a little above average.

And with two rainless weeks (10th - 23rd) I thought March would end up drier than average but two very wet days on the 27th & 28th (Storm Katie) meant that the month had way above the LTA for rainfall.

Sunshine looked like being well-below par due to a fairly cloudy first week but then things became increasingly sunnier and the month should end up by sundown this evening with around 163 hours of sunshine. This puts it just about right regarding my average March sunshine for the last 10 years of 158 hours but way above the 1981 - 2010 average of 119 hours (Sidmouth). Has March become a sunnier month over the last 10 - 15 years? It would seem so.

March 2016:
Mean minimum = 2.1°C
Mean maximum = 11.8°C
Mean = 7.0°C
Rainfall = 96.5 mm (150%!)
Sunshine = 163.4 hours.

[Greg Gruner]

March did end up colder than normal but only by 0.5C (mean max 10.4C, mean min 2.1C, mean 6.3C). So it was warmer than January and February but of course a lot colder than December with its record-breaking 10.8C. I recorded 9 air frosts. It was the first month colder than normal since September.
Rainfall was 48.9mm, slightly above normal. This despite a 13-day dry spell ending on the 23rd.

[Len Wood]

Average max 11.2C (spot on 2001-2010 average)
Average min 3.7C (-0.5 degC below 2001-2010 average)

So cold nights brought the mean temp for the month to 7.5C (0.3 degC below the average)

Rain total was 88.1 mm, 108% of average.

A funny old month with a pleasant 2 week dry spell in the middle.