Thamp

Recently got into the game and started a server save (about a week in with a lot of progress between our group) however I noticed that once winter hit, there was no winter. This is something I was hoping to experience. My world parameter when I generated the world was 256kx256k with 5k pole equator distance. I recently upped that to 15k hoping to see a decrease in temperature but so far I have seen no change. I am based around -12.7 lat in the southern hemisphere and wanted to know if there was any way I can change the climate of the area I am based in and or make winters much harsher to where they affect the equator. I have also tried changing the world spawn to see if that would affect the climates but have also seen no change.