So can anyone explain how the hot/ cold system works.......i put in insulation mods and im cold everytime it rains....
The game has a base temperature range where your character is comfortable. If the ambient temperature goes above or below that range, you start getting temperature related debuffs.
Insulation armor mods and insulating clothing don't make you warmer or cooler. They increase your tolerance to both heat and cold by widening that comfortable range. They do not make you "immune" to heat or cold. The more "insulation" you have, the hotter it can get before you overheat and the colder it can get before you become chilled.
Rain lowers the effective temperature, so if you're only barely protected from the cold, getting wet can still push you outside the comfortable range.
A player may still see hot/cold visual effects before they actually receive any meaningful debuffs. Minor temperature discomfort (visual effects) doesn't always mean the full debuffs are in play. In those cases, you may only notice increased food and water consumption rather than the debuffs.
I actually like the current system because it's a little more nuanced than the old "find a duster" and forget about environmental effects for the rest of the playthrough." There are three tiers and six quality levels of four different insulation armor and clothing mods. That affords players plenty of opportunities to improve their temperature tolerance throughout the game.
I'm not a fan of the screen effects either, but they're probably a necessary evil. Without some obvious visual warning, players would inevitably complain that they died from heat or cold debuffs because "the game never warned me." The screen effect cues let you know you're approaching the limits of your character's comfort range, even if the effects are overdone.