Microsoft's MSN Weather app forecast for South Korea in July has gone viral here for predicting nearly a full month of rain. However, the country's weather agency has said that the probability of actually having such weather is slim, saying the method the US company uses is not reliable.

Screenshots of monthly weather forecasts provided by the Microsoft website and app have spread on Twitter and in online forums. MSN Weather forecast that Seoul will be rainy for the entire month except for three days. August is also predicted to be rainy for almost the entire month.

Continuous rain is not only forecast in Seoul but also in the greater metropolitan area such as Incheon and Gyeonggi Province. Incheon is predicted to have no sunny days in July, and southern Gyeonggi Province is expected to be rainy for 28 days, according to the website.

However, the Korea Meteorological Administration dismissed the public's worries over these gloomy weather forecasts, saying they are predictions that are unlikely to be correct.

"There are a number of standards to consider for forecasting, and (MSN Weather) seems to have used only very few of them, which makes it relatively less reliable," said Woo Jin-kyu, a KMA official.

A typical climate model presents the average probability of certain weather for a certain period of time, unlike MSN Weather's forecast, which presented a specific forecast by date, he added. "The KMA predicts weather for only about 10 days, because it is scientifically unreliable to make a one- or two-month forecast."

According to the World Meteorological Organization, a strong El Nino is likely to impact Korea this summer, developing gradually between May and July. As El Nino develops, Korea statistically tends to see an increase in precipitation and lower temperatures than usual, mainly in the southern region.

However, at the same time, the KMA forecast that June and July will record similar or higher temperatures than usual, meaning there is a possibility that precipitation will increase but temperatures would remain high. Under such a forecast, Korea could see intense heavy rain for short periods, which would increase the total precipitation but not affect the temperature.