Health status red: shards?

When I opened up Kibana and noticed "No results found" I started looking into why there was no data for me to work with.

I noticed that my Elasticsearch status is red, but why?

brayn@logging:~$ curl -XGET http://localhost:9200/_cluster/health?pretty
  "cluster_name" : "elasticsearch",
  "status" : "red",
  "timed_out" : false,
  "number_of_nodes" : 1,
  "number_of_data_nodes" : 1,
  "active_primary_shards" : 1,
  "active_shards" : 1,
  "relocating_shards" : 0,
  "initializing_shards" : 4,
  "unassigned_shards" : 377,
  "delayed_unassigned_shards" : 0,
  "number_of_pending_tasks" : 0,
  "number_of_in_flight_fetch" : 0,
  "task_max_waiting_in_queue_millis" : 0,
  "active_shards_percent_as_number" : 0.2617801047120419

After enabling shard reallocation it managed to reduce the amount of unassigned and initializing shards to:

initializing_shards" : 0,
unassigned_shards" : 201,

I also deleted some very old data to possibly clear up some space, but it still gives me a red status. Am I missing something?

Noticed some indices with red health while others were yellow. They were from a month ago and of no importance so I deleted them and data is coming in again.

Elasticsearch health is yellow now