Sixth warmest October on record?

The corrected NASA temperature data for October is out here. It looks to be around the sixth warmest October on record, although interestingly (though not unexpectedly, see below), the five warmest Octobers on record are all from the previous 5 years.

I don’t normally blog on the NASA monthly data, but the tiny temporary tizzy-inspiring data entry trouble NASA had a couple of days ago warrants follow up (see “The hottest October on record?”). You can read the ongoing back-and-forth in the comments section of RealClimate’s “mountains and molehills” post.

I will wait for NOAA’s monthly National Climatic Data Center update in a few days — and then the final year end data from NASA and Hadley — before drawing any significant conclusions. But assuming these numbers don’t change much, it is worth noting that now the last two months and three of the last four have had a pretty big temperature anomaly, which suggests we may be be over the cooling effects of the La Ni±a earlier this year.

I would add that we would expect the greatest warming trend in the Arctic because the loss of sea ice exposes the open ocean directly to the air. Unfortunately, there are exceedingly few temperature stations over the Arctic. So while anomalously warm Octobers are going to be the norm, the current data sets probably underestimate northern hemisphere autumnal warming. But don’t tell that any deniers or delayers, unless you want to put them into a tiny temporary tizzy. That is NASA’s job!