No matter what happens in the remaining days of December — cold blasts, a blizzard or just business as usual — 2020 is already destined to rank as one of the warmest years on record for Richmond and Virginia.
Our warming climate doesn’t always manifest as record heat and scorching summer afternoons, though there was some of that this year.
Nor does it rule out snow and deep freezes. But an important part of this upward trend is driven by missing cool weather.
Those nights in February that ought to have been frigid, but weren’t.
August mornings that saw 70s instead of 60s.
Waiting until mid-November for fall freezes.
It all counts.
And no amount of December chill will compensate for what failed to show up last winter, at least as it counts toward the annual average.
At the end of a very mild November, about a dozen of Virginia’s long-term weather stations saw 2020 in the lead for year-to-date average temperature rankings, including Richmond.
Another dozen or so sites ranging from rural towns to big cities were in their respective top 10s. That includes Ashland, Williamsburg and West Point. The remaining sites around the state were still trending warmer than normal, most between 1 and 2 degrees Fahrenheit.
That combined effect pushed the statewide year-to-date average to the top of the rankings.
Based on preliminary data through the end of November, 2020 was Virginia’s warmest year to date, according to the National Oceanic and Atmospheric Administration. This year was running slightly ahead of 2017, 2012 and 2019, but without factoring in those Decembers. More on that below.
A warm 2020 is not unique to Virginia.
We can point to oscillating weekly and monthly weather patterns to explain some of the hot days as well as the cold spells. But the preponderance of warm weather across seasons and regions speaks to a shifting baseline.
The World Meteorological Organization recently reported that 2020 is likely to be one of the planet’s three warmest years of the industrial era, and noted that concentrations of heat-trapping greenhouse gases continued to rise despite this year’s pandemic lockdowns. Record heat was on display across oceans as well as continents. And change continues at an even faster pace in the Arctic.
Ultimately, 2019’s average of 61 degrees in Richmond ranked a close second (tying 1990) behind 2012’s all-time-high of 61.1.
(Decimal places don’t mean much for how a given day feels to us, but they are significant when we talk about a yearly average.)
And on the statewide level, last year averaged 57.5 degrees. That made 2019 Virginia’s second-warmest year behind 2012 (57.6) and just ahead of 1990 and 1998 (tied for third at 57.4).
Month-to-month variation still shows up, too.
Since last year, we’ve felt:
- persistently mild weather in January, February and March;
- a chilly April and May with a very late freeze;
- a near-normal June;
- a record-hot July;
- a stifling, muggy August;
- a cool September; and
- a mild October and a near-record-warm November.
When they average together, the number and magnitude of the warm months in 2020 far outweigh the cool ones.
To show just how much of that warm anomaly is already baked in, December would need an absurdly cold average temperature of 17.9 degrees in Richmond simply to weigh 2020 back down to our annual “normal” of 58.8.
Normal is based on the 30-year 1981 to 2010 climate period, which is due for a decadal update by NOAA next year. It’s bound to rise given the warming of the 2010s, which is another topic we’ll revisit soon. The warming stands out even more when modern weather is compared against the average for the 20th century.
Speaking of normal: What does the rest of December hold in store?
Another wave of cold air is expected for the week ahead. Federal forecasters still anticipate a period of above-normal temperatures in our region near the end of the month, but at this point it might not be enough to make this a warm December outright.
So if this month turns out to have perfectly normal levels of chilly weather, say with a mean temperature of 41 degrees for Richmond, 2020 as a whole would land in a tie for fifth-warmest year at 60.7 degrees.
And a normal December for Virginia, which is now about 39.2 degrees, would still see 2020 take second or third place in the state’s annual rankings.
If the pattern truly flips and we enjoy steady warmth later in the month, that’s really when it would start to be a photo finish.
Richmond would need a top 10 warm December, above 46 degrees, to propel 2020 decisively ahead of 2012 in the annual standings. Think back to how balmy it felt late in 2015 (or 2012 for that matter).
So while each chilly day is narrowing the chances that Richmond winds up with a record-warm year, a first-place finish for Virginia still isn’t far-fetched.
And even a below-normal December wouldn’t knock us out of the top 10.
Ultimately, a specific number or ranking doesn’t matter as much as its context, and what it says about where we’re headed.
Of the past 123 years, 10 of Richmond’s top 15 hottest happened since 2006. The urban heat island effect certainly exacerbates the warmth in and around Richmond, but it doesn’t explain the trend entirely.
With a similar period of record for statewide averages, nine of Virginia’s top 15 hottest years happened since 2002. So far in the 21st century, only 2014 had an annual temperature below the 20th-century average.
Heavier downpours are another symptom of a warmer climate in this region.
2020 is also at or near the top of the rankings for annual rainfall in many parts of the state. There’s still more time for precipitation to add up before the new year, so we’ll explore that trend separately in the weeks ahead.