Definition of ‘normal’ weather changes this week


Once-a-decade update shows QC is warmer & wetter

It happened earlier this week, but could’ve easily been missed – a small, but important change in our everyday weather forecast.

Tuesday’s normal high temperature, which has been 69° in the Quad Cities for the last 10 May 4ths, switched to 70°.

That’s just one of many adjustments in new climate data out this week from NOAA, showing an overall warmer, wetter QCA.

What does normal mean?

When meteorologists compare our weather to what’s average or normal, they’re usually referring to the 30-year average. For the last decade, that’s meant 1981-2010.

As of this week, that average switches to 1991-2020.

This switch keeps all of our average highs, lows, rain, & snow up-to-date with the current climate, & shows meteorologists & climatologists how the climate is changing.

Temperature Changes

At the local level, one of the most obvious changes is broad warming.

The Quad Cities’ average annual temperature has risen 0.5°.

10 of 12 months are now warmer than before, most notably December’s increase of 2.3°.

Precipitation Changes

The new data indicates precipitation is increasingly swinging from too much to too little throughout the year.

Average yearly precipitation rose 0.31″, from 37.96″ to 38.27″.

Six months got wetter, while the other six got drier. The biggest moisture increases were in late spring & early summer.

Snow Changes

Average annual snowfall has also ticked upward, increasing 4.5″, from 31.6″ to 36.1″.

Most of the extra snow is coming during winter’s second half, mainly January & February.

What’s the takeaway?

All parts of the year are getting warmer, especially early winter. More of our snow is now falling later in winter, and rainfall is shifting from late summer to early summer/late spring.

This data will now be the basis for what’s considered “normal” weather during the next 10 years.

In 2031, everything will update again, switching to 2001-2030 data.

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