In Genki I, になります and になりました are used interchangeably. Does になります imply "has become" and the other imply "had become"? For example,
- 夏は暑くなります。 → (This) summer has become hot
- 去年の夏は暑くなりました。→ Last summer had become hot
Also, is it natural to use になっている for "is becoming"?
Edit: This grammar is very short section in chapter 10 (section 5)