At Rakaia River Mouth over the next 24-48 hours, winds will shift from light northerly around 15 knots rising to 25 knots by midday, then easing again by late afternoon, coming mainly from the north and northeast. The sea state will become rough during periods of stronger winds but generally moderate otherwise, with a northeast swell of moderate height and period expected. Weather conditions will be mostly fine with sunny intervals initially, but increasing cloud and a rising chance of rain by late Thursday and Friday, with temperatures ranging from about 38°F to 52°F (3-11°C). Visibility should remain good except during heavier showers. Sea temperature data is not explicitly available, but coastal water in Canterbury typically ranges around 10-12°C in late August. No marine warnings are currently in place.

Regarding river and coastal conditions, Rakaia River mouth is experiencing large tidal coefficients (~91), indicating significant tidal amplitude with strong currents and notable water level variations. River water levels and currents are influenced by large tides and recent precipitation, so caution is advised for navigation close to the river mouth during peak tidal flows. Weather-driven southerly flow developing on Friday may bring colder conditions, showers mostly north of Rakaia, and snow flurries to nearby ranges around 900-1000m altitude. Sunrise is at approximately 7:10 am and sunset at 5:57 pm local time, leaving around 11 hours of daylight for safe coastal activities. These conditions will affect fishing, boating, and other coastal operations, making attention to tides, currents, and weather updates critical.