Seasonal Outlook

The seasonal outlook is updated every three months. Forecast availability is: Spring - March 1st, Summer - June 1st, Autumn - September 1st, Winter - December 1st.

Autumn 2009 UK headline: A mixed bag

Overview
A mixed autumn is expected with close to average temperatures. Possibly stormier than in recent years.

Temperature
Temperatures are expected to be close to the autumn average. The aggregated Central England Temperature (CET) for September, October and November is expected to be between -0.30C to +0.70C from the 1971-00 average.

Precipitation
Precipitation levels are expected to be close to or slightly above average. In western and northern areas we expect 90% to 110% of average.

September

Temperature: Close to or slightly below average
Precipitation: Close to or slightly above average
The first week of the month is likely to be mostly cool and unsettled with showers or longer spells of rain in all areas at times. During the second week of the month pressure is expected to rise bringing warmer and drier weather across much of the UK for a time, in the north west it may remain cloudier and less settled for much of the time. Towards the middle of the month the unsettled weather may begin to push further south again.  Temperatures slightly above average during the forecast period.

During the second half of the month a return to rather unsettled weather with wet and windy conditions developing at times.  Although there are likely to be warmer and drier spells at times these are unlikely to last for too long and on the whole temperatures will often be below the season average. Possibility of some early season snowfall over the Scottish hills towards the end of the month.  

October

Temperature: Slightly above average
Precipitation: Slightly below average
The first half of the month is likely to begin unsettled and rather chilly with spells of wet and windy weather affecting all regions at times. During the forecast period  a change to increasingly settled weather is likely, and although temperatures during the day may be reasonable there are likely to be some chilly nights with frost in places. Overall temperatures during the forecast period are likely to be close to the seasonal average.

The second half of the month is likely to start relatively settled with close to average temperatures, but for a time it may turn rather warm for the time of year. The settled weather is expected to gradually break with wet and windy weather returning to all regions by the end of the month.  Temperatures slightly above average. 


  
November

Temperature: Close to average
Precipitation: Close to average
The first half of the month is expected to begin with rather mild and settled conditions. A change to unsettled weather which is likely to persist through to the middle of the month is likely to develop reasonably quickly. Temperatures are likely to be close to or slightly above average overall during this period.

The second half of the month is expected to bring a significant change with unsettled and often cold weather developing widely. During the period we expect a significant chance of heavy snowfall affecting northern regions, with a chance of wintry conditions extending further south for a time. Temperatures during this period are likely to be below the seasonal average.  

Forecast Issued 23/09/2009

Key
Temperature
Much above average - the Central England Temperature (CET) is expected to be more than 2C above the 1961-90 average

Above average – the Central England Temperature (CET) is expected to be 1C to 2C above the 1961-90 average

Close to average – the Central England Temperature (CET) is expected to be between 1C  below and 1C above the 1961-90 average

Below average – the Central England Temperature (CET) is expected to be 1C to 2C below the 1961-90 average

Much below average - the Central England Temperature (CET) is expected to be more than 2C below the 1961-90 average

Rainfall
Much above average - expected to be more than  150% of the England & Wales Rainfall Series

Above average - expected to be between 125% and  150% of the England & Wales Rainfall Series

Close to average - expected to be between 75% and  125% of the England & Wales Rainfall Series

Below average – expected to be between 75% and  50% of the England & Wales Rainfall Series

Much below average - expected to be below than 50% of the England & Wales Rainfall Series

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