August and September 2013 were excellent months for Weatheraction. I haven't produced a spreadsheet but have followed the forecasts closely.
August was approximately 80% correct and September was 85-90% accurate. Corbyn had forecast wet and windy weather for the final weekend of September which didn't materialise (low pressure areas in the Atlantic didn't move over the British Isles as predicted); however, the rest of the month materialised very much according to the forecasts. Particularly notable was the 'Atlantic Oscillation' in the penultimate period of the month where an area of low pressure remained stuck for days in the same place, forecast by Corbyn from several weeks ahead.
The October forecast was approximately 75% accurate. One period in the middle of the month forecast dry weather for the South East of England the wet windy weather for the North West of Scotland. It turned out the exact opposite; the low pressure forecast to cause this materialised on cue but it was a couple of hundred miles out from the forecast so the weather was back to front as against the forecast. At the end of the month a severe storm was predicted for the 27th-31st and it hit at the start of this period. Also, a storm was predicted around the 21st of the month and it appeared as predicted though was not quite as severe as the forecast had suggested. Corbyn mentioned the huge storm that immediately followed the battle of Trafalgar on the 21st October 1805 and how weather history was repeating itself.