Kanji have two ways to be read 'on' reading, or 'kun' reading. Although there are MANY exceptions to these rules, the 'on' reading of a kanji is derived from the original Chinese pronunciation of that hanzi. It is used when a kanji is used in combination with other kanji characters to make a single word. The 'kun' reading of a kanji is how that word is pronounced in traditional Japanese, probably even before hanzi loanwords arrived in Japan. It's generally used when the kanji is used not in combination with other kanji.

When it is by itself, it should be "kita". When it should be read as its on'yomi, usually when it is compounded with other kanjis, it would be read as "hoku". See here for more details: http://nihongoichiban.com/2011/03/21/what-are-onyomi-and-kunyomi/ It is the same case with other characters. Common examples: 人 (hito), 木 (ki), 次 (tsugi), 間 (aida). These are all kunyomi because they are written alone.