Last updated by The POOG on March 29, 2021.
Weather is what is happening with the atmosphere and adjacent biosphere now, in a particular place. Climate is the long-term average of weather data. A 13-year simple moving average – the average of 13 years of weather data – is often used to create a single climate data point.
Weather data is ‘noisy’. It can vary considerably from day to day and location to location. Such variability hides the long-term trends that climate is trying to measure.
We have short memories, sometimes intentionally, so measuring and recording weather data over time is important to give us perspective. This article will give a historical view of weather events by category.
Severe ocean storms have a variety of names for the same weather event as explained by NASA: “Hurricane”, “Typhoon”, and “Cyclone” are all different words for the same phenomena. A major source of data is The National Hurricane Center and the Central Pacific Hurricane Center of the US National Oceanic and Atmospheric Administration (NOAA).
The Atlantic hurricane season runs from June 1st through November 30th. To get a list of storms by name by year, go to Tropical Cyclone Advisories. The Atlantic hurricanes from 1944 to 2015 are represented in Figure 1.
A longer term chart of all Atlantic storm systems is shown in Figure 2.
The modern era of satellite tracking beginning in 1979 has allowed for an accurate count of storm systems globally. Before that, information was collected from ships and aircraft encountering them as well as landfall accounts. Before the era of aircraft and global trade, storms might occur and never be witnessed. Some Atlantic storms never make landfall. The further back in time into the 19th century and earlier, the more likely that storms might be missed. One has to assume, therefore, that data in Figure 2 is incomplete, making comparison with recent data approximate.
In an old blog post in December 2012, I recorded from the NOAA FAQ of the time, the following reasons why early hurricanes are under-reported:
- [B]ecause tropical storms and hurricane spend much of their lifetime over the open ocean – some never hitting land – many systems were “missed” during the late 19th and early 20th Centuries (Vecchi and Knutson 2008).
- Starting in 1944, systematic aircraft reconnaissance was commenced for monitoring both tropical cyclones and disturbances that had the potential to develop into tropical storms and hurricanes. This did provide much improved monitoring, but still about half of the Atlantic basin was not covered (Sheets 1990).
- Beginning in 1966, daily satellite imagery became available at the National Hurricane Center, and thus statistics from this time forward are most complete.
- For hurricanes striking the USA Atlantic and Gulf coasts, one can go back further in time with relatively reliable counts of systems because enough people have lived along coastlines since 1900.
Detailed tornado data for the United States is available from NOAA’s National Weather Service, National Centers for Environmental Prediction, Storm Prediction Center. The page, Latest U.S. Tornado Statistics, has monthly severe weather summaries from 2000 to date. If you click on a year, it opens a page showing detailed tornado, hail, and wind events by month and by state. We have extracted annual totals in Table 1, below.
As may be seen from the data, 2020 was about 5% below the annual mean for the last 21 years of tornadic activity.
Typhoon activity data is hard to find. The Weather Underground has an archive but lists data only to 2018. The best source we could find was the database maintained by the Kitamoto Laboratory at the National Institute of Informatics in Japan. From it we produced a summary table of all typhoon and cyclone activity from 1951 to present. Classification of storm by category or wind speed was going to be a laborious task. Instead, we counted the number of typhoons from 2000 to present by year, the same period as for the tornado data. The average yearly number of typhoons was 36.5. The number in 2015 was just below the average at 34. In other words, like the Atlantic basin, cyclonic activity in the Western Pacific basins was slightly below average.
The Kitamoto Laboratory at the National Institute of Informatics in Japan provides data by year: Digital Typhoon: Seasonal List. However, the data is split over two Western Pacific basins and does not include the Eastern Pacific. In 2015, combined, there were 34 named storms in the Western Pacific basin. Also see Digital Typhoon: Activity Calendar (Number of Typhoons and Cyclones). The latter link gives a table of the number of days of cyclonic (typhoon) activity by month. Selecting a year gives a link at the bottom showing all the named storms for the year. Using this data we have compiled the total number of named storms beginning with 2006 although the data goes back to 1951.
- Kitamoto Laboratory. Digital Typhoon: Typhoon Images and Information
- Weather Underground. Hurricane and Tropical Cyclones.
- What is a Hurricane, Typhoon, or Tropical Cyclone? NASA. As of January 10, 2021.