Photo by Ronnie R

Just like last week, it’s going to be oppressively hot the remainder of the week, with temperatures expected to soar to 100 degrees and rising humidity to make it that much more miserable. Tomorrow’s forecast in D.C. calls for a 104-degree high, but with a heat index that will make it feel like it’s 110 degrees.

Ouch.

And, like last week, the Washington Area Metropolitan Transit Authority is going to try to offer its expectedly sweaty customers some relief, by lifting the ban on drinking water aboard Metrorail and Metrobus from today through next Monday. Per a Metro announcement:

Due to the expected extreme temperatures over the next several days, Metro customers will be permitted to carry and consume water on the system Thursday afternoon through Monday, July 2, 2012.

The exception to Metro’s “no drinking” policy applies to water only—on buses, in stations and aboard trains—and will remain in effect through system closing on Monday night. Customers are encouraged to use containers that can be tightly secured and to use trash receptacles to dispose of any waste.

That’s not the only heat-related modification coming to our municipal services. In another repeat of last week’s hot-weather stratagems, the Department of Public Works will begin trash pickup an hour earlier than usual, starting at 6 a.m. instead of 7 a.m.

This is all well and good, but Metro’s second announcement in as many weeks that it will relax the prohibition on drinking water aboard the system got us thinking. It’s going to be hot all summer. Why not just make this change permanently? Yes, Metro prides itself on operating a transit system with far less refuse than ones in other cities, but it’s just water in a long, hot summer.

But Metro says to forget about any permanent change to the no-water rule. It takes certain weather conditions for WMATA to even think of allowing its passengers to refresh themselves in the scorching heat.

“It’s not so much about it being ‘pretty darn hot,’ but rather “extreme,’ ” Metro spokesman Dan Stessel writes in an email to DCist. “While there isn’t a hard and fast rule that says 100 degrees or higher, triple-digit temps are the kind of conditions where the general manager would consider temporarily relaxing the ban.”

Stessel notes that in 2011, the temperature only exceeded 100 degrees five times. The Weather Channel projects the mercury will cross the century mark tomorrow and Saturday, and forecasts temperatures near 100 for Sunday and Monday. So riders should enjoy drinking water aboard Metro during the current spell, but not afterward.

“The prohibition on eating and drinking is one of the reasons why, for 36 years, Metro has remained one of the cleanest large transit systems in the U.S.,” Stessel says. “Today’s announcement is meant to balance our commitment to maintaining a clean system with common sense and good will.”