Lately it has felt more like a mid-western summer than a Southern California one. Humidity has been high though, to be honest, levels that are high in California are not at all high in the mid-west.

Humidity levels in Pasadena, which are similar all the way through to the Crescenta Valley, Glendale and Burbank areas, are at 69%, which is high for our area. (Just to put that in perspective, on Wednesday the temperature in Oskaloosa, Iowa was 76 degrees Fahrenheit with 95% humidity.)

You may have heard weather forecasters speak of the “monsoonal flow.” Technically, a monsoon is “a circulation system with certain well-defined characteristics. During summer, lower tropospheric winds flow toward heated continents away from the colder oceanic regions of the winter hemisphere. In the upper troposphere the flow is reversed, with flow from the summer to the winter hemisphere,” according to ScienceDirect.

“We refer to monsoonal flow as upper level winds over Southern California,” said David Sweet, meteorologist with the National Weather Service, Oxnard.

Normally the winds come from the north or northwest but during the summer there is a reversal and south-easterly winds come over the Four Corners. (The Four Corners is a region of the southwestern United States consisting of the southwestern corner of Colorado, the southeastern corner of Utah, the northeastern corner of Arizona and the northwestern corner of New Mexico.)

“It can bring rains,” he added, “drawing some rains from northern Mexico and south Arizona.”

What monsoonal flow brings is humidity, which is why we are seeing such high humidity levels.

“We see increased humidity and some showers,” Sweet said, “typically showers and thunderstorms in the mountains and desert.”

Although we don’t see mid-west humidity levels we are still experiencing the muggy feeling from the monsoonal flow.

“The next seven days look like the humidity will stay the same and at the end of the week and the weekend we will see more moisture. We are expecting a chance of thunderstorms in the mountains and deserts,” he added.

Sweet said when referring to the mountains and desert, they are talking about the top of the San Gabriel mountains into the Antelope Valley.

So we can expect the mugginess to continue and maybe even increase a little next week. The humidity does affect the “feels like” temperature. For example, on Wednesday when the temperature was 79 degrees Fahrenheit it felt like it was 81.

And to note: what happens there, affects us here. Southern California’s monsoonal flow is affected by what happens over the Four Corners where Iowa’s humidity is high due in part to its most famous export – corn.

Iowa farmers produce 2.7 billion bushels of corn every year and although it helps the economy it also makes the summer weather very uncomfortable. It comes down to the evapotranspiration, or corn sweat, process. Yep, corn sweat.

Corn pulls water from its roots and releases moisture through its leaves in the form of water vapor. An acre of corn can add up to 4,000 gallons of water vapor to the atmosphere per day. The result increases humidity, which in turn causes the heat index to increase, according to the Weather Lab, We Are Iowa.

By Mary O’KEEFE