The NIWA summary for October is now available, and as I've updated my spreadsheet of Ken's forecasts of rain and sun for New Zealand's four main centres against what actually happened. No surprises, really. He gets one out of four on rainfall, and three out of four on sunshine (being generous), which again puts him at 50% - way below his claimed accuracy of better than 80%.

Readers of NZ Geographic might notice that they've published a letter from me in response to the Brenstrum/Ring exchange in the previous issue. This is what I said...

"I read with great interest Ken Ring's defence of his "moon method" of weather forecasting in NZG #81. I've also been taking a look at how well Mr Ring's forecasts work, and have reached conclusions very similar to Erick Brenstrum (NZG #79). Mr Ring's almanac provides "estimates" of monthly rainfall and sunshine hours for many towns in NZ, and I have compared his forecasts for the four main centres with the actual outcomes (taken from NIWA's excellent monthly climate summaries) for the year to date. So far, he is doing no better than the easiest forecast - that rainfall in any given month will be the same as the long term average. His success rate (marked generously) is about 50%, or little better than chance. I've posted the full details on my "Ringworld" blog, which also includes details of an analysis of Ring's weather maps for 2005 by NIWA scientist Jim Renwick. Mr Ring's maps bear the same relationship to the actual weather at the time as maps selected at random from the same period in previous years. Mr Ring is a staunch defender of his forecasts. "I can prove they work about 85% of the time" he wrote in his riposte to Brenstrum's analysis in NZG #81, yet we now have three separate and independent analyses which suggest they work no better than chance. If Mr Ring is to retain any credibility as a weather forecaster, he should produce his proof, or ask his publishers to label his almanac as a work of astrology, to be placed in that section of the nation's bookshops."

Still no news from Ken about the studies that support his claim.