This is what the PHB (p. 183) says about Heavy Obscurement:
A heavily obscured area—such as darkness, opaque fog, or dense foliage—blocks vision entirely. A creature in a heavily obscured area effectively suffers from the blinded condition
The Errata released to clarify Heavy Obscurement states:
A heavily obscured area doesn't blind you, but you are effectively blinded when you try to see something obscured by it.
The Errata doesn't specify "suffers from" however while the PHB does.
If I'm attacked from an area of heavy obscurement, am I under the effects of the blinded condition?
An example would be if an archer fired an arrow through Fog Cloud at myself who is not in Fog Cloud.