2018 In Review: Part Three: Recap

Usually this time of the year, expert climatologists from NOAA and NASA produce an analysis of the state of the climate for the previous year. Unfortunately, due to the federal government shutdown, this will be delayed for some time. There are other organizations that produce reports, using the same underlying data. This includes the United Kingdom’s Met Office, as well as the Berkeley Earth group out in California. While I’m not taking anything away from those two organizations (they do great work!), it just doesn’t feel right when NOAA and NASA aren’t around to give their analysis.

There is a small silver lining in that most of the data used in these reports are still being updated at the National Centers for Environmental Information, and if you know your way around the site, you still have access to it. Back in December, I provided a preliminary analysis of precipitation and temperature, and where particular stations stood so far in the context of its period of record. Also, Brian Brettschneider, a climatologist from Alaska, produced some excellent GIS maps a few weeks ago describing the state of the 2018 climate using NCEI data. In this post we will provide updates, using the latest available data. It will not be comprehensive, but it is hoped to provide a general overview. And with that, the following disclaimer:

DISCLAIMER: This data and analysis is considered unofficial until vetted and verified by expert scientists from NCEI. Also, we hope that they (and all federal employees) will return to work soon. We appreciate those employees who are still working unpaid, and we are in full support of everything you do.


According to Brian’s map, there appears to be a U-shape of warmth, as both the eastern and western sides of the country experienced some of their warmest years (80th percentile and higher). Most of the warmth occurred in the western part of the country, including Alaska. In my temperature analysis back in December, I noted three Alaskan stations (Kotzebue, Utqiagvik (Barrow), and Bethel) were in the top 5 warmest stations, when you compare departures from normal, rather than absolute temperatures. 2 of those stations were able to hang on in the top 5 as we finished out the year (Bethel dropped, but still remained in the top ten):

  • +6.7F: Kotzebue, Alaska

  • +6.3F: Hermit, Colorado

  • +5.5F: Utqiagvik (Barrow), Alaska

  • +5.5F: Fontenelle Dam, Wyoming

  • +4.7F: Jaqueline Cochran Regional Airport, California

Kotzebue stood out as the warmest station in the United States, having overall temperatures 6.7 degrees above normal. Edgemont, South Dakota, who initally placed 3rd on the coldest station list, became the coldest station at the end of the year. They experienced temperatures 5.1 degrees below normal, and had a whopping 43 nights where they experienced the coldest night on record. Speaking of records, here are the final tallies on the 4 types of temperature records analyzed.

  • Daytime high record warmest

    • 423 Stations with more than 10 days broken (56 more than 20).

    • Station with most records: Opihihale, Hawaii (86)

  • Daytime high record coldest

    • 370 Stations with more than 10 days broken (10 more than 20).

    • Station with most records: Cumberland, Maryland (27)

  • Overnight low record warmest

    • 922 Stations with more than 10 days broken (282 more than 20).

    • Station with most records: Thibodaux, Virginia (61)

  • Overnight low record coldest

    • 123 Stations with more than 10 days broken (4 more than 20).

    • Station with most records: Edgemont, South Datkota (43)

Finally, below is a snapshot of daily temperature anomalies for each day in 2018. This provides some context on the spatial and temporal differences in temperature, as well as to insights as to why the final annual results ended up the way it did.

Daily temperature departures from normal for the United States, each day in 2018. Source of Data is  PRISM Climate Group:  Oregon State University.

Daily temperature departures from normal for the United States, each day in 2018. Source of Data is PRISM Climate Group: Oregon State University.


While one of the biggest stories is that the eastern United States experienced numerous record rainfall years, it should be pointed out areas in the western part of the United States were at their all time driest. Certain parts of Oregon and Colorado were in the top ten percentile of driest years. Death Valley, California is known for its extremely high, record breaking summertime temperatures. 2018 was no different in that regard, but it was also interesting to see it was one of the driest stations in the country. In 2018, it received less than an inch of rain (0.92” total), which is 1.44” below normal (2.36"), which puts it at about 39% below normal. It wasn’t its driest year (0.41” in 1994), but it is certainly in its top 5 driest.


In the initial December post on precipitation, it was noted that 207 stations were within 10% of beating its record, 85 within 5% and 10 within 1%. In just the last few weeks of the year, 82 of these stations were able to have enough rainfall to be considered wettest on record. Most of these stations occurred in the southeastern U.S, including North Carolina, Virginia, and the Washington DC metro area. The location of the final results are below. 21 stations beat their previous record by 10” or more, and the largest margin is held by Wilmington, North Carolina, who broke its previous record by 28.79 inches.


Because of all the rain that fell in December, the top 5 wettest stations were shook up a bit during the final weeks, here are the tallies:

  • 214.4%: Ajo, Arizona

  • 212.6%: Marion, North Carolina

  • 198.3%: Tripoli, Iowa

  • 198.1%: Sibley, Iowa

  • 196.3% Canton, SD

A little bit of rain fell Arizona at the end of the year, which pushed Ajo into one of the wettest stations for the year, a good chunk of rain came after the monsoon season in October, as remnants of two tropical systems helped dumped rainfall in the area. This was recently highlighted in one of my “Better Know a City Climatology” posts.

One more thing…

Something I didn’t show previously, and is a weather variable I care about deeply, is dew point, which is a metric for atmospheric humidity. I personally hate high dew points, as it leads to a lot of agony when the atmosphere is not able to evaporate all the sweat that comes from high temperatures (I’ll leave it at that). Using PRISM data, it’s amazing to watch this illustration of dew point throughout the year. It shows how moisture from the Gulf of Mexico rises into the eastern half of the United States during the summertime, and then retreat back by the end of the year.. It truly is not the heat, but rather the humidity.