GA pilot reported near miss with a hang glider during cruise flight. Pilot took evasive action to avoid a collision and stated there were several hang gliders in the area flying through clouds causing airborne conflicts.

Narrative

Flying on course from the YONMA Fix direct OMMNI Waypoint; about 3.6 miles southwest of the PUNQU Waypoint; I encountered a hang glider at my 12 o'clock opposite direction at the same altitude. I advised ATC that I would be making a turn and climb to avoid him. Prior to commencing a turn and climb; I saw an additional hang glider about 150 ft at my 10 o'clock at 4;000 ft (now 100 ft below). Looking back to my now 3 o'clock on a 310 heading and about 200 ft at 4;000 (still 100 ft below) popping out of a cloud. At this time; there are now three (3) hang gliders all at 4;000 flying into and out of clouds. Within 3 minutes of seeing and taking evasive maneuvers; I advised ATC that I was clear of conflict and continued back on course.The weather conditions in the area of the incident were SCT 4000 ft with the clouds being cumulus clouds with tops of about 4500-5000 ft. In the location; the clouds were roughly 200 ft to the North and 100 ft to the West.No conflict alert was given by ATC due to the hang gliders not appearing on RADAR.No other issues were encountered for the remainder of the flight.