Tracked live by the FAA, but its flight plan was first seen after takeoff, so we don't know the scheduled time and can't say whether it's late.

UNITED · FLIGHT UA 1938 LANDED 2:00 PM ET, ~2 MIN LATE · SCHEDULED TIME UNKNOWN

UA 1938 · JAX → IAD

took off 12:38 PM ET · landed 2:00 PM ET (scheduled time unknown)
Forecast issued Tue 10:00 PM ET · 9h after departure

Odds over time

Arrive at IAD more than 15 minutes late?
10% chance · ±0 pts −1 pt · 24h
HOW SURE WE ARE Very high. The odds now come almost entirely from live conditions.
WEATHER FORECASTS LIVE IN THE AIR 0% 5% 10% 15% 20% 12h 6h Departs Lands