Climate and weather

Local and regional differences

Weather and climate vary from region to region and within regions. For example, the Bay of Plenty is sheltered by high country on three sides, so the region tends to be sunny and calm. The opposite occurs in the Taranaki region – it bears the brunt of westerlies coming in from the Tasman Sea and is one of the windiest places in the country. The Canterbury region has five different climate zones due to the influences of the Southern Alps to the west and the Pacific Ocean on the east.

Variations in climate

There are variations in climate caused by natural oscillations. A climate oscillation is a recurring climate pattern. There are three natural oscillations that influence New Zealand weather and climate. Each oscillation lasts for a different period of time.
The oscillation we hear about most often is the El Niño Southern Oscillation (ENSO). Surface waters in the central and eastern Pacific Ocean become warmer than usual, and this affects atmospheric conditions. During an El Niño event, Aotearoa usually experiences stronger westerly winds in summer, which leads to rain in the west and drier conditions in the east. During winter, southerly winds cause colder temperatures. El Niño events occur every 2–7 years and last around a year. During La Niña events, the country experiences warmer air temperatures, more rain in the northeast and reduced rainfall in the southwest.
The Interdecadal Pacific Oscillation (IPO) has phases that last around 20–30 years. Its phases affect the strength and frequency of El Niño events. The Southern Annular Mode (SAM) can bring unsettled stormy weather to New Zealand. SAM phases are short – lasting for a few days to a few weeks.
The atmosphere, which surrounds our planet, is a huge blanket of air. To exist, all living organisms on this planet rely on the atmosphere. It provides us with the air we breathe and protects us from the sun’s harmful rays. If we didn’t have this blanket of protection, we’d be burned alive by the heat of the sun during the day and frozen at night. As a result, it is this mass of air that has kept the earth’s temperature manageable.
The state of the atmosphere, like clear or foggy, hot or cold, peaceful or stormy, is described by the weather. The troposphere, the lowest layer of the planet’s atmosphere immediately below the stratosphere, is where most weather events occur on Earth. Weather refers to daily temperature, precipitation, and other atmospheric circumstances, whereas climate refers to the long-term average of atmospheric conditions. 
Weather is influenced by changes in air pressure, temperature, and moisture. These changes could be caused by the Sun’s angle at any given point, which varies with latitude. The largest scale atmospheric circulations are caused by the huge temperature difference between polar and tropical air. Weather events in the middle latitudes, such as extratropical cyclones, are caused by instabilities in the jet streamflow. Because the Earth’s axis is tilted with respect to its orbital plane, sunlight strikes the globe at various angles throughout the year. Changes in Earth’s orbit can have a long-term impact on the amount and distribution of solar energy received by Earth, influencing long-term climate and global climate change.
Climate is the long-term weather tendency of a location, which is typically averaged over 30 years. It is the average and variability of meteorological variables over time periods ranging from months to millions of years. Temperature, humidity, air pressure, wind speed, and precipitation are just a few of the meteorological variables that are recorded on a daily basis. Climate refers to the state of the Earth’s climate system as a whole, which includes the ocean, land, and ice. The climate of a location is impacted by its latitude/longitude, topography, altitude, and proximity to water bodies and currents.
Climates are classified according to average and usual parameters, the most common of which are temperature and precipitation. The Köppen climate classification system was the most widely used. The Bergeron and Spatial Synoptic Classification systems are interested in the origin of air masses that define the climate of a region.