"Feels like" temperature explained (New Zealand)
Why the number on your forecast often differs from the air temperature — and how MetService combines wind chill and humidity to tell you how the day will actually feel.
The “feels like” temperature on a MetService forecast is what the air feels like on your skin once wind and humidity are taken into account, not just what a thermometer reads. On a cold, blustery Wellington morning it can sit several degrees below the air temperature; on a muggy Northland afternoon it can climb well above it. The actual air temperature drives your body's heat exchange, but wind and moisture change how fast you lose or hold that heat.
Why isn't the thermometer reading enough?
A thermometer measures the air. Your body cares about the rate at which it swaps heat with that air. Wind strips away the thin warm layer your skin builds up, so a 5°C day in a stiff southerly feels far colder than 5°C in still air. Humidity works the other way in the heat: when the air is already laden with moisture, sweat evaporates slowly, so your natural cooling stalls and 26°C can feel oppressive. The “feels like” figure folds both effects into a single, more honest number.
How does MetService calculate “feels like”?
MetService uses two regimes and switches between them depending on the temperature. In colder conditions it applies a wind chill calculation that accounts for the cooling power of the wind. In warmer conditions it uses an apparent temperature that accounts for the sultriness you feel when perspiration can't evaporate efficiently on a warm, muggy day. There's a roll-over between roughly 10°C and 14°C where the formula transitions from one to the other.
The apparent-temperature calculation MetService uses takes three inputs: the air temperature, the average wind speed measured 10 metres above the ground, and humidity (expressed as water-vapour pressure). One quirk is worth knowing: if the maths ever produces an apparent temperature lower than the actual air temperature, MetService simply reports the air temperature as the “feels like” value instead. In other words, the number is designed to reflect real discomfort, not to undercut the thermometer artificially.
Wind chill: the southerly effect
New Zealand sits squarely in the mid-latitude westerlies of the Southern Hemisphere — the belt sailors know as the Roaring Forties — and cold southerlies sweeping up from the Southern Ocean are a defining feature of our winters. Wind chill is why a forecast can read 7°C while feeling like 2°C: the stronger the wind, the faster exposed skin loses heat, and the larger the gap. For anyone tramping, cycling or working outdoors, the “feels like” figure is a better guide to layering than the air temperature alone.
Humidity: why summer can feel worse than the number
In the warm half of the year, humidity is the key driver. When water-vapour pressure is high — common in the upper North Island and during periods of moist northerly flow — sweat evaporates slowly and your body struggles to shed heat. That's when the apparent temperature runs above the air temperature and a 27°C day feels closer to 30°C. It's also why the same air temperature feels far more comfortable in dry Central Otago than in humid Auckland.
| Condition | Main driver | Effect on “feels like” |
|---|---|---|
| Cold and windy | Wind chill | Feels colder than the air temperature |
| Cold and calm | Little adjustment | Close to the air temperature |
| Warm and humid | Apparent temperature | Feels hotter than the air temperature |
| Warm and dry with a breeze | Evaporative cooling | Can feel a touch cooler and more comfortable |
How should you use the “feels like” number?
Treat it as your dressing and exertion guide. In winter, layer for the “feels like” figure, not the air temperature — the gap is where people underestimate the cold and get caught out in the hills. In summer, use it to judge heat stress: when apparent temperatures run high, ease back on strenuous activity, hydrate, and take shade. It's the single most practical number on the forecast for deciding what to wear and how hard to push.
Does the “feels like” figure matter for children, older people and pets?
It matters most for those least able to regulate their own temperature. Young children lose heat faster than adults, so a windy “feels like” figure well below the air temperature is a better guide to how many layers they need. Older people and anyone with a heart or respiratory condition are more vulnerable to heat stress, so a high apparent temperature on a humid day is a cue to slow down, stay hydrated and seek shade. The same logic applies to pets and livestock, which feel the bite of wind and the weight of humidity just as we do. In short, the “feels like” number isn't a novelty — for the people and animals in your care, it's often the more important of the two temperatures on the forecast.
Why do different apps show different “feels like” values?
Two reasons. First, providers may use slightly different formulas or humidity inputs. Second, the underlying air temperature and wind each app starts from can come from different forecast models — the European ECMWF, the American NOAA GFS or the German DWD ICON — which don't always agree. When those models diverge on wind strength or temperature, the derived “feels like” values diverge too. checkweather.io lines those models up side by side and grades their agreement into a plain-English confidence score, so you can see when the “feels like” number is well anchored and when it's still up for grabs, with MetService linked as the official national source.