Why Was It So Mild Last Month?

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By Paul Homewood

It was unusually mild last month in England. According to the CET, it was 3.0C warmer than the 1961-90 average.

Global warming, I hear you cry. Well, maybe, but things are not quite that simple.

The first thing I should point out is that, although the 1961-90 average was 5.7C, the more relevant average for 1981-2010 was nearly a full degree warmer, at 6.6C.

The second thing to note is that last month was not the warmest on record. The warmest March was way back in 1957, with 1938 in second place.

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This gives a clue that we are observing a “weather” phenomenon, rather than a “climate” one.

A look at the distribution of daily temperatures gives some further clues as to what is going on.

Below is the “normal” distribution of days within temperature bands, based on the 1961-90 baseline.

Although the average mean temperature for this period was 5.7C, it is worth noting that the most common band is 7C to 7.9C. The next most common is 6C to 6.9C.

In other words, days when it is a degree or two warmer than average are perfectly common.

Now let’s add this year’s distribution:

For a start, we can see that there have been no days below 4C. (The coldest day was actually 4.8C). In an average March (1961-90 baseline), there would be 11 days colder than this.

At the other end of the scale, we find that the number of days above 8C has been much higher than average this year.

What is really interesting though is when we compare this March with those other warm ones in 1957 and 1938.

We can see that the distributions are extremely similar in those years as last month.

And, indeed, the weather was also very similar in 1938 and 1957.

In both of those years, there was persistent high pressure to the east, which pulled in south-westerly winds, and also led very dry weather over the east of the country.