The Selwyn District has a vast geographical landscape and is a predominantly rural area located on the eastern side of the South Island, just south and to the west of Christchurch. Selwyn spans right from the Pacific Ocean by Lake Ellesmere (Te Waihora), to Arthur's Pass, located in the heart of the Southern Alps. Due to the vast environmental extremes that Selwyn hosts, the climate of certain areas in the district can differ drastically.
Starting at the far east of the Selwyn District on the coast line, near Rakaia Huts and Lake Ellesmere (Te Waihora), you can often expect to see coastal climate conditions. For much of the year, the temperature is moderated by a cool north-easterly sea breeze.
Inland, near the more central areas in Selwyn, such as the Rolleston and Lincoln townships, the climate is very dependent on the lie of the Southern Alps. Summer temperatures are warm, with the highest temperatures occurring when hot dry north-westerly winds blow over the Alps, down into the plains. During the winter months the climate is often cold, with overnight frosts a frequent occurrence. Over these months south-westerly winds tend to blow over the Alps running a cold chill through the plains.
The alpine environment tends to be sporadic and often unpredictable. Throughout the winter, areas such as Arthurs Pass and Castle Hill are subject to heavy snow, strong winds and low temperatures. Over the summer months, the temperatures tend to be much cooler in the Alps when compared to the plains. Don't be fooled though, Sheffield and Springfield can still experience temperatures around 25 degrees in summer!