Climate Insights for Gretna

The climate in Gretna is temperate. The average annual temperature is 11°C and approximately 994mm of precipitation falls per year. Gretna receives a notable amount of rainfall throughout the year, including during its driest month. Gretna is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: July, June, August. The coldest months are January, February, December, when temperatures can drop to -8°C. Snowfall occurs from January to December, with around 86cm accumulating over the season.

Gretna has a wide annual temperature range, spanning 39°C from the coldest to warmest months. The warmest month is July, when average highs reach 31°C and the mean temperature sits around 25°C. The coldest month is January, when overnight lows fall to -8°C and the daily average is -4°C. On average, daily temperatures fluctuate by about 11°C between overnight lows and afternoon highs. The sharpest temperature change occurs between September and October, with a 9°C shift in average temperatures.

Gretna is a moderately rainy area, receiving approximately 994mm of precipitation annually, which averages out to around 83mm per month. The wettest month is May, averaging 156mm of rainfall. June and August also tend to see above-average precipitation. The driest month is November, with just 32mm. That's 124mm less than May, the wettest month. Precipitation varies noticeably between seasons, with the first half (January to June) of the year generally seeing more rainfall. Snowfall is a regular feature from January to December, with around 86cm accumulating over the season. February typically sees the most snow at around 24cm.

Gretna is relatively calm, with an average annual wind speed of 4km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is April, averaging 5km/h, though still comfortable for most outdoor activities. The calmest conditions occur in July, with average winds dropping to 3km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 2km/h between the calmest and windiest months.

It is currently spring in Gretna, which began on March 20, 2026. Gretna is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in July at around 31°C, while the coldest stretch bottoms out in January near -8°C. Summer is next, beginning on June 21, 2026 — 7 days from now.

The best time to visit Gretna is during September, when the weather is most comfortable for travellers. During these months, average temperatures hover around 21°C with modest rainfall averaging 99mm per month. By contrast, July can be uncomfortably hot with highs reaching 31°C, while January is the coldest period with lows dropping to -8°C. Despite being the best months overall, some rain is still likely — pack a waterproof layer and plan a mix of indoor and outdoor activities.

The table below shows monthly climate averages for Gretna based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.