Aidan the cat goes hunting on a lovely spring day. (John Brighenti/ Flickr)

Are you feeling a bit more thirsty than usual today? If so, that’s probably because it’s quite dry in the lower levels of the atmosphere. Afternoon temperatures easily jumped into the mid- to upper 60s, but dew points remained stuck in the teens to low 20s, creating a relative-humidity value of about 20 percent. That’s pretty dry, especially when you consider the thickening cloud cover occurring this afternoon ahead of an approaching frontal boundary. Nevertheless, 60s in March counts as a win in my book, and it’s a good reason to get outside and enjoy the fine weather this evening. Just make sure to bring some water!

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Tonight: Clouds will continue to build through the evening and overnight, eventually resulting in overcast skies late tonight. The increase in cloud cover combined with a light south wind (5 to 10 mph) will keep things mild. Overnight lows will range from 46 to 51 degrees, with just a slight chance at a stray shower or two toward daybreak.

View the current weather at The Washington Post.

Tomorrow (Monday): A weak frontal boundary will slowly pass through the region Monday morning, probably stalling out for a few hours. Where you are relative to the front will make a huge difference in the temperature. Mostly cloudy in the morning hours, before light rain moves in by the afternoon. High temperatures in the mid- to upper 50s in and around the District, with clearer skies and warmer temperatures south of the city. Rain showers will generally end by midnight, with gradual clearing and colder temperatures. Lows in the low to mid-30s.

See Brian Jackson’s forecast through next week. And if you haven’t already, join us on Facebook, and follow us on Twitter and Instagram. For related traffic news, check out Gridlock.

Rare tropical storm forms off coast of Brazil: The south Atlantic Ocean is not a conducive environment for tropical storm or hurricane formation. Nevertheless, on Sunday morning, Tropical Storm Iba formed about 600 miles northeast of Rio de Janeiro. High wind-shear values and unfavorable baseline convection are two major reasons that this ocean basin was thought (up until the 21st century, at least) to be incapable of supporting the development of tropical systems.

Iba won’t threaten mainland Brazil and will probably remain a weak tropical storm for the next few days as it meanders away from the coast and into open ocean. From there, the storm will encounter some cool water and quickly make the transition to an extra-tropical system.

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