Sunday, March 3, 2013

another St. Louis winter in St. Paul

This year's low temperature: -13F on February 1st.  Image courtesy of

Now, thirteen degrees below zero may sound awfully cold, and it sure feels that way when you have to get up early in the morning, go out into the dark and catch a bus in the blowing wind.  Thirteen below is no picnic.  But it's not the historical norm for the Twin Cities.

 -13F was where our temperature  bottomed out on February 1st this year, and I'm going to be the first one to call it the low for the winter, as we're pretty unlikely to get that cold again at this  point in March.  The 10 day forecast is calling for highs above freezing, so I think that's about it for old man winter.

The reason that -13F is  significant, is that  it puts this winter, in the Twin Cities, in the zone 5b category.  That is, a winter where  the minimum temperature is between -10 and -15F.  If we were still using the 1990 USDA zone map which was the standard until recently, we would expect a yearly minimum temperature between -25 and -30 to hit us some night in late January or early February.  The fact that this hasn't happened in most of the last 15 years is significant.

I've always found maps fascinating, and when I was starting to become interested in gardening and horticulture and later landscape architecture, I pored over the 1990 USDA zone map, finding the growing zones of places I had been and thinking through what plants I had seen and what color the soil was and making a mental map of what grew where, and what could be expected in a similar place.

People talked about global warming, but it was just a theory, and nobody was really sure if it would really affect us, say nothing about whether it was really real.

And now- a decade or two later, in the Twin Cities, we are on a regular basis having the kind of winter that  was formerly expected in St. Louis or Kansas City  or Indianapolis.

detail of the 1990 USDA zone hardiness map
Take a look at the graphic above.  It's from the 1990 zone map.  Yes, the new and improved map has put the Twin Cities in 4B, with some tiny urban pockets in 5A.  But I don't think that goes  far enough.  Zone 5b is the greenish-yellow band running through the middle of Missouri and Illinois and Indiana.  That is now here.  That used to be 500 miles south of here.  It leapfrogged Iowa in two decades and is now is making itself at home in our yards in St. Paul and Minneapolis on a pretty regular basis.

I can't complain about the less-cold winter.  I kind of like it really.  It's the summers and the uncertainty about the future that's disconcerting.  My zone 5 sweet cherry tree is thriving and I'm expecting a good harvest  of  apricots  from my backyard tree this year.   I'll probably plant a peach tree at our rental place.  But will I be able to grow blueberries any more?  While it's not an edible, I've noticed that the once reliable Astilbe now dies to the ground in our intense summer heat the last few years, and  it usually doesn't come back.  Is this a taste of what's coming?

The new pests that the warming trend is encouraging are pretty disturbing too.  The new invader, Spotted-wing drosophila shouldn't be able to thrive here, but it is.  An old-school Minnesota winter might have set the Emerald Ash borer population back a bit, but this one won't. 

If you've followed this blog for any time, you know that I'm a skeptic when it comes to the future availability of cheap oil.  So I'll forgive you if you are about to say that the coming of peak oil will offset climate change and everything will be fantastic.

Yes, growing peaches in Minnesota is fantastic, and we may someday be growing mangoes here if current trends continue and water supplies stay relatively intact.  Because peak oil doesn't mean that there are no more hydrocarbons available.  Alcoholics don't usually decide to go cold turkey when their  favorite brand of sauce isn't available.  They switch to Listerine or Lysol or Sterno or whatever else fills the bill.  So too with hydrocarbons.  There's still a lot of coal and peat and firewood in the world and it'll all get burned in short order by oil addicts needing a fix.

Add that to the inertia of the warming trend that would continue for decades even if we did somehow go cold turkey, and it's clear that we need to learn to adapt.  The alternative isn't something to consider.

There clearly isn't going to be any sort of voluntary consensus to reduce the greenhouse gases by us or any other county or combination thereof.  'Our Way of Life is Non-Negotiable' as one charming former Vice President said it.  So it is being negotiated for us, by the atmosphere, at terms that are less than advantageous to the human species.  Can't say we didn't ask for it.  


  1. Hey Jeff - Thanks for putting this info together. When you pay attention, it is not difficult to see the changing climate., and I agree that I kinda like it :( We are lucky to live where we do in the sense of water, and still being able to maintain something that resembles a 4 season year - even with shifting zones. Mangoes and figs in MN,what does it mean for the rest of the country??

    1. Hi Andy- Yes, I think a lot of Minnesotans enjoy the warming climate and we're likely to be better off than most (say, Arizona or Texas) in the long term. Apparently we're the fastest warming state in the country, so I hope that doesn't also translate to more frequent and deeper drought. Updraft had a good article on it a week ago or so that's worth looking at.

      As for mangoes- if it gets that warm in my lifetime, I'm guessing that the sandhills of Nebraska will be drifting across the Twin Cities and filling in the lakes- making gardening a bit more challenging.

  2. Speaking of St. Louis winters ... when I moved to St. Louis in 1984, every winter would feature at least one low below zero F. In 1985 it got down to -18F one fine winter morning. Lows at or below -10F continued to occur through the rest of the 1980s and into the early 1990s at least. But then things changed.

    The last time the official lowest temperature of the winter dropped below 0F here in St. Louis was in 1999. Let me repeat that: 1999, thirteen years ago. Even the 2012 USDA zone map puts St. Louis solidly in the middle of zone 6, meaning we should drop to between 0F and -10F occasionally. But in fact we haven't reached that temperature range in thirteen years. Even the current USDA zone map is out of date!! And it gets worse. Until the last two winters, we've dropped to 0F or within a degree or two of that at least once during the winter. Last winter, however, the official lowest temperature recorded in St. Louis was 13F. This winter, the lowest we've gone is 9F. This would put us near the border of Zone 7 and 8 in terms of on-the-ground climate. That's Atlanta territory according to the 1990 zone map. On the one hand it means I can overwinter plants like parsley in the open garden, something I haven't been able to do before. I plan to try planting tea shrubs (Camellia sinensis) this year to see if they will overwinter. But on the other hand, I expect to lose some plants as well. White pines in my backyard and elsewhere in the area are succumbing to the one-two punch of drought and heat. And I have to expect further change, more plant mortality, and further difficulty in knowing what and when to plant given that more warming is already built in based on the last thirty years of fossil fuel use.

  3. Hi SLClaire,

    It's interesting to hear that what's happening in St. Louis parallels what is happening in St. Paul. We still have cold winters, but a lot less cold on average than they once were. If I were there, I might try growing figs or lemons or even some hardy bananas.

    On the down side- yes- even here I see white pines struggling, and other taiga species that have survived as far south as the Twin Cities are not going to be here for long, I fear. The drought plays a role, as does the heat, and both are likely human-caused. I do wonder sometimes how long it will be before the sandhills of Nebraska dry out enough to become mobile again and blow east, toward Iowa and Minnesota.

  4. Hey Jeff! Didn't know that you had a blog- Gita shared the address. That's awesome! Look forward to "visiting" you every once in awhile. :)

    1. Thanks Anne- Gita told me she posted this on facebook today and I noticed a spike in visitors. Hope you enjoy the blog!

  5. Jeff thank you very much for weather pattern information. Yes, It's hard to find out what to expect in next 24 hours, we can have four season in one day.