Temperature

Temperature is a feature that was introduced in The Sims 2: Seasons and incorporated into The Sims Castaway Stories. It is also present in The Sims 3: Seasons and The Sims 4: Seasons.

The Sims 2: Seasons
Temperature in The Sims 2: Seasons is measured on a scale of -100 to 100. This scale is applied to indoor temperature, outdoor temperature, and Sims' internal temperature. Within that range, it is divided into five zones.

Indoor temperatures are comfortable unless a room is open to the outside weather. This can happen if there is no roof, or if a room contains a stairway to a rooftop deck, or if there is a gap in an exterior wall. Players should note that, while a gable on a gable roof is high enough to serve as one wall of a room, and wall coverings can be applied to it, the game does not consider it a wall when deciding whether a room is open to the outside. Sims who are at work, school, or at college classes are considered to be in a comfortable area.

The outdoor temperature is invisible, but does have some visible effects. Below -20, ponds freeze and snow may fall. If the outdoor temperature is cold or very cold, Sims may change into outerwear before going outside, and visitors, walk-bys, and townies may appear in outerwear. Outdoor temperature does not change during the day, but drops at night. It also drops during rain, hail, and snow. Reading the weather forecast in the newspaper or watching the weather channel on television may give some information about the outdoor temperature.

Swimming pools are heated, and are comfortable regardless of the temperature.

The Sims 3: Seasons
Temperature in The Sims 3: Seasons uses real-world scales, and can be set to display in either Fahrenheit or Celsius. As in its predecessor, temperature has positive or negative effects on Sims and causes visual changes to the environment.

Effects on Sims
Sims will not be affected by temperatures in the mild range, as that is considered to be the comfortable range. When the temperature climbs into the warm or hot ranges, Sims will receive moodlets related to high temperatures. If the temperature gets too high, Sims may suffer from sunburn, or even spontaneous combustion. Likewise, when the temperature falls into the cool or cold range, Sims will receive moodlets related to low temperatures. Sims who are exposed to low temperatures for too long may become sick, and may even freeze.

Effects on the environment
As mentioned earlier, the temperature will also affect the environment. For example, temperatures in the hot range will cause a heat haze to be visible. Likewise, when the temperature is in the cold range, frost will gradually form, and lakes and ponds will freeze over. Accumulated snow will not melt as long as the temperature remains in the cold range, but lakes, frost, and snow will start to thaw as soon as it rises out of this range.

The Sims 4: Seasons
Like The Sims 2, The Sims 4: Seasons does not use real-world temperature units. Sims that are too cold can warm themselves up by using campfires, heat lamps, fireplaces, or by putting on cold weather outfits. However, they can overheat if they're not careful. If they get too warm, they can cool down by swimming, using lawn water slides, hydrating, standing under a ceiling fan, or putting on hot weather outfits.

At extreme temperatures such as "Heatwave" or "Freezing", Sims will feel temperature effects indoors. There is a chance for them to burn or freeze to death unless they wear hot/cold weather outfits at all times, or there is an active thermostat on the lot. Sims who are at work, school or an otherwise off-world place are considered to be indoors with an active thermostat.

Vampires (from The Sims 4: Vampires) and ghosts are immune to temperature changes. They will not automatically change into hot or cold weather outfits, as they do not need them.

Temperature levels and effects
There are six different temperature levels, ranging from "Freezing" to "Heatwave":