September 2018 Weather Round-Up

The day-to-day weather has very little impact on the volume of visits to Jersey, but can play a major role in influencing the types of activities that visitors who are here do, and thereby, the amount of money that they spend.  Some attractions and activity providers thrive only when the sun shines, others see higher patronage on rainy days.

The following data tables show the monthly profile of temperatures, rainfall and sunshine over the past three years, the annual change, and finally the variance to the thirty-year average.  When looking at the monthly figures warmer temperatures, drier weather and higher sunshine hours are shaded green, and when looking at comparisons a warmer, drier and sunnier relative outcome is shaded green.

september weather

September 2018

September was warmer, drier and, in particular, sunnier than is typically the case.

The average temperature in September was 16.8oC, which was 1.4oC warmer than the year before and 0.3oC above the thirty-year average.  Rainfall totalled 36mm for the month, 94mm drier than September of last year and 27mm less rainfall than the seasonal norm.   

Looking at the number of hours of sunshine we find that the total of 243.8 hours, meaning that September was in fact a sunnier month than was August, plus it was 69 hours up on September of last year and 51 hours above the seasonal norm.

Averages can be misleading – you can have many values that are a bit below normal being offset by a single value that is significantly above normal.  In meteorological terms for example you could have a month during which 28 days see not a drop of rain, but three days of torrential downpours.  Statistically this might lead to an ‘average’ amount of rainfall for the month, but most visitors would not have experienced ‘average’ weather.

Looking at September there was only one day, the 22nd, with no recorded sunshine, and a run of six days towards the end of the month with around ten hours of sunshine each day.  The lowest minimum temperature was around 7oC on 25th September.  September 17th saw the warmest temperature of the month at 26oC. 

There were 23 days on which no recorded rain fell with a further three days on which only trace amounts fell.  By far the wettest day of the month was Saturday 22nd September with a tally of 26mm, meaning that three-quarters of the monthly total accrued in just a single day.

September Weather Data