Invercargill has a temperate oceanic climate.
The mean daily temperature ranges from 5.2 °C (41.4 °F) in July to 14 °C (57 °F) in January. The yearly mean temperature is 9.8 °C (49.6 °F). Rainfall averages 1,112 millimetres (43.8 in) annually, and measurable snowfall is occasionally seen during the winter months of June to September. It is the cloudiest city in New Zealand with only 1,580 hours of sunshine per annum. Despite its cloudiness, and a relatively high frequency of rainy days, Invercargill receives less rain than either Auckland or Wellington. Invercargill is also New Zealand's second windiest city, after Wellington.
The average temperature high ranges from 18.7 °C (65.7 °F) in January to 9.5 °C (49.1 °F) in July, but temperatures do occasionally exceed 25 °C (77 °F) in summer with a recorded extreme of 32.2 °C (90.0 °F).
Owing to its relatively high latitude (46° 42′), the city enjoys nearly 16 hours of daylight at the summer solstice in late December. Conversely, the city receives only around 8 hours of daylight at the winter solstice in late June.
Invercargill is the "City of Water and Light". The "light" refers to the long summer twilights and the aurora australis (southern lights). The "water" reference, humorists suggest, comes from notorious horizontal, driving rain in high wind at the corner of the two main streets, Dee and Tay. A recent sign also states "Invercargill, where dreams can come true" with an image from the 2005 film The World's Fastest Indian.
In September 2010, Invercargill's heaviest snowfall in living memory heralded a run of unseasonably cold weather.
A few buildings were damaged, notably Stadium Southland, the roof of which collapsed under the weight of the snow; and a decorating store. Many other stores were shut, and Invercargill Airport was closed for a day.