Why has March been so cold in Modesto? Here’s how recent weather compares to normal

Don’t put away your winter coat just yet. While winter is technically over (the spring equinox was last week), the cold weather in Modesto is not going away just yet.

If this March has felt colder to you than it typically does, that’s because temperatures in the area have actually been lower than average.

Here’s what the numbers look like:

March 2023 compared to past years

This month ranks as the fourth coldest March in history dating back to 1927, based off of the average overall temperature, according to the National Weather Service.

The average overall temperature to date has been 51 degrees in March, said meteorologist Idamis Del Valle-Shoemaker said. The normal iis 56.4 degrees. The average overall temperature takes into consideration both the highs and lows.

So far, the average observed high this month has been 59.4 degrees with an average observed low of 42.8 degrees.

The normal high in March averages 68.2 degrees and the normal low averages 45.2 degrees.

What’s causing the cooler temperatures in Modesto?

Modesto Junior College Earth Science Instructor Noah Hughes said the most likely cause of the colder-than-normal weather is La Niña.

La Niña is a pattern of below-normal sea surface temperatures in the topical Pacific Ocean, Hughes said. Stronger than usual trade winds push warm water toward Asia, causing upwelling that brings cold water to the surface of the Pacific Ocean off of the coast of North America.

“This deflects the jet stream up toward Alaska before it plunges down along the West Coast, bringing cold Alaskan air toward the West Coast of North America,” Hughes said. “This is why La Niña years are usually colder than average.”

Hughes said La Niña winters are also typically drier than average in California, but this winter was different.

“For some as-of-yet unknown reason, the strong La Niña ridge of high pressure set up further west than usual,” Hughes said. “This allowed the jet stream to steer out our storms over the waters of the eastern Pacific before slamming them into California, bringing us much more precipitation than we would usually expect from La Niña ocean conditions.”

This is California’s third winter in a row of La Niña conditions, Hughes said.

What we can expect this week

Modesto residents may want the “rain, rain (to) go away” and not come again another day, but they should expect to see more this week.

“A strong winter storm will bring widespread moderate to heavy precipitation to the region (Monday night) into Wednesday,” Del Valle-Shoemaker said. “We’re expecting anywhere from a quarter of an inch to a half inch for the Modesto area.”

Temperature will be 10 to 15 degrees cooler than average Tuesday with highs in the mid-50s, the meteorologist said. Wednesday will see similar temperatures.

Thursday, Del Valle-Shoemaker said temperatures will be 10 degrees below normal with highs in the low 60s.

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