Sunshine up but temperature down yesterday also September summary

With 6.7 hours of strong sunshine, Tuesday was a dry and typically autumn day. However, the wind, mainly from the west-nor-west was from a cool direction and pegged back the maximum to 14.9C, down 1C on the Monday maximum, which was fractionally above the 33-year average, with light winds peaking at 16mph.

A cool night followed as the thermometer fell away in light winds to a minimum of 6.6C, which was 0.7C below the October average.

This morning is bright and dry with thin cloud restricting any strong sunshine.

September 2017

If you got the impression that September was a wet month, you were correct. The statistics prove it was a very wet month with total rainfall amounting to 75.0mm, which was 13.5mm above the 33-year average and the wettest September since 2008. The maximum fall was 8.7mm on the 24th.

To look a little closer into the data I find that we only had 6 dry days when the average, since my station started in 1984, is 16. What a contrast with the 26 dry days in September 2003. There were 17 days classed as wet days with the rainfall equal to or greater than 1mm. In total there were 7 days with modest totals from 5 to 7mm.

Not only was it a damp month but not surprisingly, a cool month, due to the above average cloud cover. The mean temperature was 0.6C below the 33-year average. To analyse the data a little further, the average maximum and minimum were 0.7C and 0.4C respectively below the long-term average. Only 5 days were above the average temperature.

There was a warm spell at the beginning of the month with a peak of 22.0C on the 4th. In contrast were the very cool nights at the later end of the month with the coldest night on the 22nd with a minimum of 2.2C, giving a brief grass frost.

Much of the blame for this disappointing start to autumn can be blamed on a number of passing low-pressure systems. The average barometric pressure for September was 3mb below the long-term average. There was a particularly wet and windy period in the middle of the second week with strong winds gusting to 39mph on the 12th. The exact opposite occurred on the 25th being a very calm day with little wind and a maximum gust of just 8mph.

Fog was evident on 5 mornings with visibility down to 200m on the 26th and mist prevalent after dawn on 4 days at the end of the month.

Sunshine during September amounted to 115 hours varying from 9.22 hours on the 1st to no sunshine at all on the 3rd and 25th.