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Environmentby Brew Editors9:15 amSep 4, 20180

Baltimore summers: Hot now and, in 22 years, much hotter

An analysis shows how the number of 90 degree days here has risen since 1960 – and will keep rising in the future

Above: A police officer gives a man water on a hot day in Baltimore last week. Temperatures were in the 90s and with humidity the heat index was over 100 degrees. (Fern Shen)

Feeling like it wasn’t always this hot, Baltimore?

You’re right, it wasn’t.

In 1960, Baltimore had on average 18 days where the temperature was 90° or higher. Today, the Baltimore area can expect an average 25 days at or above 90° each year.

By 2040, we’re looking at 39 of these scorching days annually – and by 2090, 50 such days.

The latter would mean that across the roughly 150 days of summer (May through September), every third day would be 90 degrees or over.

So says the New York Times in a recent report, with an interactive feature allowing the user to enter a U.S. city and get past and current data.

Click on the graph below to see it in more detail.

By the year 2090, scientists consulted by the New York Times said, Baltimore summers will have, on average, 50 days when the temperature hits 90 degrees or higher.

By 2090, a group of scientists predict that Baltimore area summers will have, on average, 50 days when the temperature hits 90 degrees or higher. That translates into about three 90-degree-plus days every week during the summer.

“The Baltimore area is likely to feel this extra heat even if countries take action to lower their emissions by the end of the century,” according to the Times analysis.

It was conducted for them by the Climate Impact Lab, a group of climate scientists, economists and data analysts from the Rhodium Group, University of Chicago, Rutgers University and the University of California, Berkeley.

“If countries continue emitting at historically high rates, the future could look even hotter,” the Times report, published last week, says.

The earliest data available for Baltimore in the interactive chart seen above is from 1960. The most recent is from 2017.
For those interested in the project’s METHODOLOGY, here’s how The Times explains it:

For each year, the count of days at or above 90 degrees reflects a 21-year rolling average. Temperature observations for your hometown are averaged over an area of approximately 625 km² (240 square miles) and may not match single weather-station records.

The time series is based on historical data for 1960-2000. The 2001-2020 period relies on a combination of historical data and future projections.

After 2020, the data uses a mixed climate model that captures a broad range of extreme temperature responses. The “likely” future range reflects outcomes with 66 percent probability of occurrence in the RCP 4.5 scenario.

The data does not include locations with fewer than three 90-degree days per year on average or for selected other regions where day-to-day variation in maximum temperature is underestimated by the model.

A still more detailed methodology is available from Climate Impact Lab.

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