4:00 p.m. update: The temperature has leveled off at 46 degrees and the next hour will be the last daylight hour with temperatures in the 40s for at least a week. Arctic air is on the brink of spilling into the region.

Today’s high temperatures will probably end up as 46 or 47, which is 3-4 degrees above normal (43) or 6 to 7 degrees above the inauguration average high of 40. The noon temperature of 40 was 3 degrees above the average inauguration swearing-in temperature of 37. This morning’s low was 33, but is unlikely to be the low for the day as subfreezing air arrives prior to midnight.

3:00 p.m. update: The sun has come out and the mercury has responded - with a relatively comfortable 46 degrees in D.C. CWG’s Jamie Jones - reporting from the parade - says it feels great in the sun, but if you’re watching the parade from the shady side of the street (south), it’s kind of chilly. Temperatures might rise 1 or 2 more degrees, but as winds pick up late this afternoon and darkness approaches, our transition towards the deep freeze commences.

Evidence of those lucky ones in the sun. Cc: @capitalweather lockerz.com/s/278510392

— Jamie Jones (@jbjonesjr) January 21, 2013

2:00 p.m. update: A little sunshine has emerged, and, as people line D.C.’s streets for the inaugural parade, the temperature is up to 44 degrees. We could rise a few more degrees before temperatures begin a slow, steady plunge.

Overview: It’s a brisk one in Washington, D.C., but those headed out for President Obama’s second inauguration festivities are fortunate the bitter cold air holds off until tonight and tomorrow. After lows this morning in the low 30s (33 at Reagan National Airport), temperatures should climb to near 40 for the noon swearing-in and into the mid-40s by mid-afternoon for the inaugural parade.

Link: Inauguration weather history

It will be cloudier than not (the sun may make the occasional appearance), with a slight (20 percent) chance of a light rain shower or snow flurries, especially late. Winds aren’t too bad, generally from the south at around 10 mph until this evening.

The weather turns markedly less benign this evening. An arctic front blasts through the region and winds pick up out of the west and northwest, reaching 10-20 mph with some gusts up to 30 mph. Snow flurries and snow showers cannot be ruled out (30 percent chance). Temperatures tumble below freezing by 10 p.m. with wind chills dipping into the teens and 20s. Dress accordingly, inaugural ball-goers.

Earlier updates

1:00 p.m. update: The mercury is up to 42 in Washington, D.C. under mostly cloudy skies. Satellite imagery shows streaks of clouds oriented southwest to northeast which may erode briefly at times this afternoon, perhaps allowing some peeks of sun during the inaugural parade (2:30 p.m.).

12:30 p.m. update: Obama’s inaugural address included a lengthy mention of climate change and his commitment to address it. Excerpt:

We will respond to the threat of climate change, knowing that the failure to do so would betray our children and future generations. Some may still deny the overwhelming judgment of science, but none can avoid the devastating impact of raging fires, and crippling drought, and more powerful storms.

12:00 p.m. update: The official noon temperature in Washington, D.C. for President Obama’s swearing in was 40 degrees. This is just three degrees above the January inauguration noon average of 37. Several other past inaugurations have experienced similar temperatures although sky conditions have varied:

* 1949: Mostly sunny and windy, 38 (Truman)
* 1965: Cloudy, 38 (Johnson)
* 1973: Cloudy and windy, 42 (Nixon)
* 1993: Sunny, 40 (Clinton)

Temperatures are on pace to reach the mid-40s this afternoon.

11:00 a.m. update: No movement in temperatures from the previous hour due to overcast skies. The temperature at Reagan National Airport remains 38. The noon swearing-in temperature should be 39 or 40 degrees - on track with earlier projections.

Sun trying to break through overcast skies just north of the White House @capitalweather #inauguration twitter.com/camdenwalker/s…

— A. Camden Walker (@camdenwalker) January 21, 2013

10:00 a.m. update: Temperatures have risen into the mid-to-upper 30s (38 at Reagan National Airport) but are being held somewhat in check by a blanket of cloud cover. Radar even shows a little light snow falling from the clouds but it’s evaporating before reaching the ground. Don’t be totally shocked to see a stray snowflake or a sprinkle over the next couple hours but it’s predominantely dry. The better chance of snow flurries comes this evening.