One of the more entertainingly troublesome effects in investment behavior is that of recency bias. It describes how we humans over-weight recent effects, and under-weight similar things that happened serially before them. For example, if something dramatic has happened in a commodity recently, we might not remember something similar just a few weeks earlier.
Consider the case in U.S. snow cover. If you had asked me this morning whether the U.S. had more, less, or about the same percentage snow cover as it did this time last year, I would have said “more”. Why? Mostly because of the recent storm in the U.S. northeast, one that seemed earlier and larger than I remembered having this time last year.
That was, of course, dead wrong, as the following figure shows (using NOAA data). Not only does the U.S. have a lower percentage of snow cover than it did last year at this time, it is lower than the prior two years as well.