There's no real catalyst for the euro rally today but some broader USD weakness is making its way through, likely due to a slip in bond yields on the failure to get through 3% on 10s.
The FOMC begins its two day meeting today so there could be some position squaring in euro shorts or we could be seeing flows. ECB President Lagarde participates in a Eurogroup meeting at 2 pm ET but that's not likely to be a market mover or an appropriate place to shift monetary policy expectations.
If this move is to pick up into something sustainable, it will need to get above the April 29 high of 1.0593.