The winter of 2012 has been anomalous here in southeast Michigan. Warm, warm, warm. All winter long. It’s a little frightening, knowing how we need cold freezes to kill back certain pest species, to reset the clocks for certain plant and crop species. It’s a little frightening, knowing how temperatures help regulate tree bud production, so that they don’t erupt too early and the little fruits get frozen off by late cold snaps.
But I’m a science guy. I wanted to know HOW warm it’s been. Is it my imagination, or did January feel more like February? Did we just skip January’s weather altogether? I want data!
So I got some data. Bottom line: We did skip January. And more. Let’s go over things a bit, starting in December and running til March 11, when I started gathering this data (hence, my spreadsheets stop there, unless I do an update sometime in the future).
About the Data:
I went online, and used a variety of sources. Because there are lots of sources to choose some, including some very local ones (like the Adrian Airport, just a few miles south), it was tough. But in the end I chose to report on weather station KDTW, which is at the Detroit Metro Airport, because it has a long historical record (back to 1874). And this report is not so much about our precise weather at Dragonwood, so much as about the weather all of us here in the Midwest have been through of late. I downloaded daily temperatures and made plots. You could do this too.
Let’s look at a graph of southeast Michigan year-round average temperatures.
What do we see? In round numbers,
1. Summer peak daily average temp is around mid-70s.
2. Winter peak daily average temp is around mid-20s. This is about 50°F lower than the summer.
3. In the fall and spring months, temperatures fall and rise quickly, about 10-12°F each month in Sep-Nov, and Mar-May.
What we don’t see? How much monthly variety there is from year to year. Answer? Not that much. The majority of months average within 2-3°F of their long-term average. It’s a fairly rare month that is as much as 4-5°F above or below average. On the average, roughly 80% of months fall within about 4-5°F of the normal, leaving those extra warm or extra cold months as outliers in the top or bottom 10% of records.
Example: this past November 2011 at KDTW, average temps were 46.6°F, which was 5.1°F above normal. That was the 5th highest November average temperature in 130+ years of record keeping. So November was really warm, as Novembers go.
Warm winter. Really warm.
December: 5.4°F above normal (12th warmest on record):
So, what do we see? First, the “normal” green solid line is the mean average temperature across the month, just like the imaginary line down the middle of the annual graph for KDTW up above. Just eyeballing it, you can see that the average December “normal” temperature is about 30°F.
The daily data is the three wiggly lines representing daily high, low and mean (average) temperatures for last December. Again, it’s easy to see that it was a warm December. I’ve added a “2012 averaged” red dashed line that is a rough estimate of how much warmer than normal the month was. Detail: it’s an 11-day moving average line, meaning the value represents the average of that day plus those of 5 days before it and the 5 days after it. For the month as a whole, we averaged 5.4°F above normal (normal is 30.1°F).
January: 5.1°F above normal (17th warmest on record):
January average daily mean temp is 25.6°F. January 2012 however averaged 30.7°F, a good bit higher. In fact, astute readers will note that the January average temperature was actually just a tad warmer than the normal December is supposed to be.
We skipped January, in weather terms.
February: 4.5°F above normal (12th warmest on record):
February is normally almost as cold as January: just 3°F warmer, averaging 28.1°F. But this February was a whopping 32.6°F, again being warmer than the average December, let alone Jan or Feb.
March: ??°F above normal (?th warmest on record):
March normal average temp is 36.9°F at KDTW. So far we’re well above that, and the month is nearing the halfway mark, with nothing but warm weather forecast. Normally, this is maple sap weather, with nice warm days, but good freezes on most nights. And you can see two good freezes, the second one around March 9-10. But that looks like the end of our season. Without further nightly freezes, there’s no sap to flow from our sugary friends, and with extra warm days the maple buds get ready to bloom and end the season altogether.
Note: Observant readers will note that I can’t have a valid red-dashed moving average line for the March 6-11 end of the graph, because I would need data from March 12-17 in order to calculate it. So just ignore this… I’ll post an update in April with the full month of data for March.
Quick Look at the Region:
Here’s a look at December temperatures across the US. The top map is mean temperature: SE Michigan is running about 35, and it’s the expected cold-in-the-North pattern. But it’s the second map below that shows what it means. For each tiny point on the map, the colors indicate how much warmer or colder the area was in December compared to “normal” years (monthly mean temps). In short high numbers (red and brownish colors) mean hotter than normal temperatures. Roughly two thirds of the country had a hotter than normal December. The Dakotas and Minnesota were about the hottest.
There are other maps for the other months, but this post is too long already. Go look them up yourself in the links below. Short story: we stayed hot.
I think the best way to look at this winter so far is this: Spring has been shifted backward nearly a month. It’s mid March now, the peepers are peeping madly, the robins woke us up this morning, the crocuses are well displayed, and I got buzzed by a honey bee yesterday. This is all a bit early for us.
On the plus side: the deer had an easy winter, and didn’t chew up our young fruit tree branches like usual.
On the flip side: the fruit trees might bud too early and get nipped by a “normal” frost (ie., if the fruit trees bud early, it doesn’t have to be a “late” frost to nip the buds. Even a regular frost can do the job.
There’s probably fifty plus and minuses we could do here, but I’m done.
Enjoy the nice weather.
As I post this it’s March 13, and we’re clearly in a very warm spell that will kill our maple season. No freezes since last Friday, none in the forecast. So the maple sap run will definitely be over for us… hope you got started early this year (our maples started dripping in late January! we got tapped on February 4, two weeks earlier than ever for Dragonwood). I’ll follow up with a full March report later, in April. Remind me if you don’t see it.
Oh! And don’t forget if you haven’t been there, the USDA released their new Plant Hardiness Map a few weeks ago (here’s a write-up about it from Mother Jones), and it’s interactive this time, click to get your own state map. Our farm? Surprise! We’ve moved from Zone 5 to Zone 6 (a more southern, warmer zone). Here’s the direct link to the map at the USDA.
Data Reference Links:
1. US Temperature Anomaly Map (from NOAA):
2. Monthly Climate Report For DTW Airport, Detroit (by NOAA; 12 months available):
3. Seasonal Weather Averages Plot (available for many localities, from Weather Underground):
4. History Data (Weather Underground) - really powerful ability to bring up nice graphs of the temperature and other weather facts for just about anywhere in the U.S., with customizable date ranges. BETTER YET: at the bottom of each page is a tabular version of the data, and a link to get it all as CSV (comma separated variables) that you can plug into a spreadsheet, like Open Office (what I used):
5. Historical local daily averages and record high/low temps (NOAA) - this is for DTW Airport, but other places and other dates are available. Look around:
6. NOAA Climate data from all over the U.S. - this is the site that leads you to #5 above. Just click an area on the map, then click the tab for “Local Data/Records” and follow links to the data you want. Different areas have different kinds and amounts of data, depending on the local weather recording stations: