Besides questions about thunderstorms, the questions I get asked the most are: what will the weather be like on Halloween, or Christmas? Together with this question, I often get asked, or told stories, about what other Halloweens and Christmases were like. Well, it’s a little too early to start talking about Christmas, but with Halloween just around the corner, I figured it was time to pull out some of the information about Halloween weather that I have written on over the years and have another look at it.

It seems like every year when Halloween rolls around, I hear radio shows about what the weather is going to be like on Halloween, or I overhear discussions as I go about my everyday life. Almost always, the discussion turns toward previous Halloweens and just how bad they have been. It seems, if you listen to most people, that Halloween has had more than its share of bad weather. So I thought it might be kind of interesting to look back and see if this is another case of selective weather memory, or if maybe, just maybe, Halloween does bring on bad weather.

To carry out this study I utilized our three main data sources: Winnipeg, Brandon and Dauphin. First of all, let’s look at the averages and records for Oct. 31 in Table 1.

By looking at these values, you can quickly see that nearly all of the extremes for this date have occurred fairly recently. This might help explain why most people remember Halloween as having bad weather: rain, snow, cold. It is also interesting that very few people seem to remember how nice it was in 1983 and 1999, when we had record highs for that date.

This data is only a snapshot of this date and doesn’t really tell us if Oct. 31 has more than its share of bad weather. For this, I had to go back through all of the data for Oct. 31 and crunch it down to see just what that date is like, and this is what I found.

The first thing I discovered was that the vast majority of “bad” weather on Halloween has occurred recently. Starting in 1950 I only found one bad year during the ’50s and that was in 1955. During the ’60s the weather was very nice and no bad weather days occurred. The 1970s started off with a couple of bad years in 1971 and ’72, where temperatures were rather cold across all three regions. Also, it was in 1971 when Winnipeg experienced its heaviest Halloween snow cover (I can vaguely remember going out trick-or-treating with snow past my knees). The rest of this decade saw nice Halloween weather and this nice weather continued into the ’80s, but by the middle of that decade, temperatures dipped once again, with cold Halloweens in 1984 and 1986.

Then the 1990s came and agricultural Manitoba saw what was probably the worst Halloween weather. In 1991, all three regions saw record-low temperatures along with record snowfalls in Brandon and Dauphin. Later in this decade, 1996 saw cold temperatures, and rain dampened Halloween festivities in 1997 and ’99. These cool and wet conditions continued into the new century, with 2000 seeing rain at both Winnipeg and Brandon, while Dauphin experienced rain in 2001. In 2002, 2003, 2006 and 2007, temperatures were the story, as subfreezing temperatures were the rule, along with some light snow.

From a purely statistical point of view, Halloween has exactly the same chance of seeing precipitation as any other day (about 30 per cent), and if precipitation does fall there is about a 50/50 chance that it will fall as snow – not much different than the odds on Oct. 30 or Nov. 1. Temperature-wise, Oct. 31 is not statistically colder or warmer than the days before or after it, so it looks like the recent stint of bad Halloween weather can be blamed for everyone thinking Halloween brings on bad weather.