Now that Memorial Day is approaching, our most common question we get at the National Weather Service is "what's the weather going to be like this weekend?" After all, this is the start of the summer camping season for many of the denizens of the Inland Northwest. Before folks hear the answer, they often have the preconception that weather in this part of the country really doesn't become conducive for prolonged outdoor activities until early July. With that notion in mind, we decided to take a climatological glimpse of what Memorial Day weekends in the past truly delivered.
Usually looking up weather over holidays is easy. The 4th of July always falls on the 4th day of July, and Christmas always falls on December 25th. For Memorial Day though, the days varied from year to year, however before 1971 and the passage of the Uniform Monday Holiday Act, Memorial Day always fell on May 30th. Consequently, what constituted the Memorial Day Weekend isn't exactly clear. To make things simple we decided to only look at Memorial Day Weekends from 1971 and beyond. These dates can range from May 23rd through May 31st.
|500 mb mean map 5/23-5/31|
That map alone suggests the region still might be prone to wet weather so what are the climatological temperatures and chances for precipitation for this time of year? We will start by looking at data for Spokane. But knowing that many people like to get away from the metro area and go camping in the woods, we also decided to look at the weather at the Priest River Experimental Station in north Idaho. Here's a map of where that station is located
And here are the averages:
So not bad. An average high around 70°F with rain expected on roughly 1 out of 4 days doesn't sound too terrible. But that's climatology. Now here's reality. Lets start on a positive note and look at the top 10 warmest Memorial Day Weekends. Here is the list for Spokane.
|Top 10 warmest Memorial Day weekends for Spokane.|
|Top 10 warmest Memorial Day weekends at Priest River experimental station.|
Now let's look at the list of least desirable Memorial Day weekends. For Spokane there were 5 extended weekends which saw the average temperature stuck below 50°F or roughly 10°F colder than normal. The worst year (by temperature) was 1975, however the rainfall that year was light (there were trace amounts of rain which fell on 2 of the 3 days). Perhaps 1989 could be considered a worse year for outdoor activities considering an average temperature of 48°F and just over an inch of precipitation.
|Top 10 coldest Memorial Day weekends for Spokane.|
Now lets look at a few daily extremes:
Hottest High Temperature: Spokane 94° (May 29, 1983)
Priest River 91° (May 24, 2003)
Coldest Low Temperature: Spokane 35°* (May 26, 1991, *last of several occurrences)
Priest River 29° (May 30, 2011)
Wettest Day: Spokane 0.79" (May 28, 1988)
Priest River 0.96" (May 29, 2010)
Wettest Weekend: Spokane 1.20" (May24-26, 1997...it rained all three days)
Priest River 1.58" (May 29-31, 2010...it rained all three days)
Percent of entirely dry Memorial Day weekends: Spokane 19%
Priest River 23%
This last tidbit is a little unexpected since Priest River is typically a wetter location than Spokane. The answer may lie in the fact that the Spokane observation is taken at least once an hour through the day, whereas the Priest River one is taken once a day. Thus if a trace of rain fell at sometime during the day and it wasn't witnessed it might be recorded as a dry day. Nonetheless, the odds of seeing an entirely dry Memorial Day weekend in the Inland Northwest (especially the eastern third of it) is not good.
Will this weekend be one that sees dry and warm weather? Looking at the latest weather maps, the answer is a resounding no. Here is our latest forecast issued at 3pm today (Tuesday 5/20)
For Spokane it looks like at least a 20% chance of precipitation each day with temperatures cooling to right around the seasonal normals.
|Sandpoint outlook...Priest River graphs are not available|