The chance of El Nino forming during 2017 has recently increased according to the latest El Nino Southern Oscillation (ENSO) wrap-up released by the Bureau of Meteorology on the final day of summer. So, what are the chances of El Nino forming this year and what would this mean for weather in Australia? The Pacific Ocean is currently shifting towards an El Nino-like pattern, with warmer-than-average sea surface temperatures near South America for the first time since June last year. The atmosphere above the Pacific Ocean is also beginning to show signs of the early stages of El Nino. Despite this behaviour in the ocean and atmosphere to the east of Australia, it is too early to tell whether or not we are actually heading towards towards an El Nino. While a number of computer models suggest the Pacific Ocean will continue to warm towards El Nino in coming months, there is too much uncertainty in these forecasts. The models used to monitor ENSO have less accuracy at this time of year and their forecasts should be taken with a grain of salt. The Bureau of Meteorology currently give a 50 percent chance of El Nino forming during 2017 and have upgraded the ENSO outlook status to El Nino Watch. This will increase to Alert later in the year if the likelihood of El Nino increases to 70 percent or more. El Nino events typically start and end in autumn and have their greatest influence on Australian weather during winter and spring, although they can stray from this average timeline. The most common effects of El Nino in Australia are reduced rainfall across the eastern states and increased temperatures in much of the south and east, particularly later in the year. El Nino can also increase the risk of frost in parts of eastern Australia, delay the monsoon onset and reduce cyclone numbers in the tropics, increase fire danger in the southeast and decrease the snow depth and season length in Australia's alpine region. The next ENSO outlook will be released by the Bureau of Meteorology on the 14th of March.