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Waterloo’s new 30 year climate data

Earlier this month, the National Oceanic and Atmospheric Administration (NOAA) released its new set of 30 year climate normals. NOAA looks back at the past 30 years of weather to determine the daily normal temperatures, monthly normals, and yearly normals.

First, we take a look at Waterloo's normals, starting with temperatures. Click for Dubuque -- Cedar Rapids -- Iowa City

Over the past 30 years, the normal monthly temperature has been warmer than the previous 30 years. The highest jump is December -- 3.1°.

Let's take a look at the normal monthly maximum/minimum temperatures.

The trend is warmer. So, it's no surprise that the normal annual temperature is also up, a little more than 1°.

The trend of warmer temperature also leads to changes in the annual precipitation. The differences in temperatures leads to stronger storm systems with more moisture.

Here's a look at the comparison of the normal monthly precipitation.

Interestingly, the months of March, July, August and November have had less precipitation between 1991 and 2020 compared to 1981-2010. All other months have had more, especially in June and September.

This of course translates to a higher yearly total as well.

There has been an interesting shift in snowfall for Waterloo. Previously, the snowiest month was December, but new data indicates the most snow usually falls in January. Also, January and February have trended upward, with the earlier and later months of the season seeing roughly the same snow.

Also interesting to note, May's normal is now 0.1". This is because of one snowfall of 1.7" in May of 2013.

The normal annual snowfall has also increased.

The bottom line -- warming temperatures have led to more extreme weather (record cold, record heat, record snow, record rain). While it may not be as cold in the winter, it's still cold enough to snow -- more snow than in previous years. In fact, out of the top 10 snowiest seasons on record in Waterloo, eight have occurred since 1991.

Climate Central put together this map showing that most of the United States has experienced a warming trend over the past 120 years (left) and 30 years (right). In the last 30 years, the northern Plains states were the only areas with near the same or slightly cooler temperatures.

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Kyle Kiel


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Brandon Libby


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Joie Bettenhausen


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