Average date of last frost of Spring + first of autumn

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Average date of last frost of Spring + first of autumn

Postby Darren Rogers » 2013 Oct 08, 20:13

I have been in a discussion with others on how best to calculate the average date of the last frost of spring and the first of autumn

does anyone do this and if so how?

The others wanted to have an excel spread sheet to do it but I prefer pen+paper and came up with this:

is that in each year a number is allocated to the date of the last frost ie: 1st Jan' would be 1, 2nd Jan would be 2, 1st Feb would be 32 and as per the example below we get a mean number

1.) 1st June = 152 (that is the 152nd day of the year)
2.) 4th April = 94 (the 94th day of the year)
3.) 3rd May = 123 (the 123rd day of the year)

now add together 152+94+123 = 369
now divide 369 by 3 (No. of years) = 123

so we can say after those 3 years the date of the last frost in the spring was on average the 3rd May.

any suggestions welcome
Darren Rogers
Maulds Meaburn
Cumbria (Half way between Shap and Appleby)

http://www.mauldsmeaburnweather.co.uk
Darren Rogers
 
Posts: 145
Joined: 2011 Nov 27, 20:22
Location: Cumbria - half way between Shap and Appleby in the Eden valley

Re: Average date of last frost of Spring + first of autumn

Postby Len Wood » 2013 Oct 09, 19:27

Hello Darren,

I just take the date of first frost as the number of days from 1st Jan. i.e. 1 to 365.
In the winter 2011-2012 my first frost was not until 1st Feb the following year, so this went down as day 397.
My average for first frost since my records began in 1985 is day 334 which is 30th Nov.

I do all this on an Excel spreadsheet.
Len

Wembury, SW Devon coast
N50.33 W4.13
Altitude 83 m asl
Len Wood
 
Posts: 349
Joined: 2012 Jan 28, 16:12
Location: Wembury, coastal SW Devon, 83 m asl

Re: Average date of last frost of Spring + first of autumn

Postby Graham Easterling » 2013 Oct 10, 08:43

Moving on slightly, the frost free periods in Penzance over the last 21 years range from:-

211 days in 1995
to
365 days in 2002 - (something to be allowed for in any frost free period macros!)

Also, a bit of a 'Pembroke Dangler' this morning, the 1st one for a very long time.

Graham
Penzance
Graham

Penzance Weather Station
Grid Ref:
SW464231 - Post Code: TR18 4TP
19m AMSL - Aspect SSE
In a SE - NW orientated valley

23 Years of Penzance Weather Records : http://penzanceweather.atspace.com/weather.html
Graham Easterling
 
Posts: 316
Joined: 2011 Nov 30, 20:29
Location: Penzance, Cornwall

Re: Average date of last frost of Spring + first of autumn

Postby Darren Rogers » 2013 Oct 10, 12:13

Thank you - good stuff - and worthy of note re the 'delayed' periods of frost.

At present the longest that I have had to wait in autumn for an AF is 8th Nov', although in 2013 I'm still waiting.
Darren Rogers
Maulds Meaburn
Cumbria (Half way between Shap and Appleby)

http://www.mauldsmeaburnweather.co.uk
Darren Rogers
 
Posts: 145
Joined: 2011 Nov 27, 20:22
Location: Cumbria - half way between Shap and Appleby in the Eden valley


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