[FALSE] Did the China Meteorological Administration predict that the coldest Spring Festival of Guangdong province in history is around the corner and the temperature is expected to drop below zero degree celsius?

A screenshot of the weather forecast post about wind chill which has been widely circulated.

Outline

• It was predicted that this year will be the coldest Spring Festival in the history of Guangdong province and the temperature was expected to drop below zero degree Celsius on New Year’s Eve.
• It was claimed that they cited the information from China Meteorological Administration (CMA), but actually CMA had no relevant predictions. In other words, the cited source is inaccurate. According to the actual forecasts and historical data of the CMA, we found that the average temperature of 21 cities in Guangdong province during the Spring Festival this year was between 12.7°C (lowest) and 20.4°C (highest), slightly higher than that of previous years. As for New Year’s Eve (Feb. 11, 2021), the predicted average low temperature was 12.7°C.
• The Guangdong Provincial Meteorological Public Service Centre stated on its official Weibo page that Guangdong is “unlikely to experience the coldest Spring Festival this year based on the analysis of monthly climate prediction.” Moreover, the Hong Kong Observatory stated that the forecasted temperature ranges for two consecutive days should overlap in the actual temperature forecast. The data quoted in the post, such as the temperature ranges of two consecutive days on New Year’s Eve (Feb. 11) and the New Year’s Day (Feb. 12) did not overlap at all. Therefore, there were obvious scientific mistakes in the post.
• Thus, the claims of that “the coldest Spring Festival” and “the temperature will drop below zero degrees Celsius on New Year’s Eve” are both FALSE.

News Brief

Recently, a weather forecast post about wind chill has been widely circulated on local social media platforms. According to the information, the CMA predicted that Guangdong province will witness the coldest Spring Festival and reminded everyone to take measures to keep warm. It also attached the daily temperature forecast around the Spring Festival from Jan. 23 to Feb. 17, 2021. According to the data, the predicted minimum temperature on February 11 and February 15 was around -2°C.

Fact-Checking

The claim questions: Is it true that the CMA predicts that the coldest Spring Festival of Guangdong is around the corner, and the temperature on New Year’s Eve will drop below zero degrees Celsius?

In this post listed a detailed temperature forecast data for the period of January 23 to February 17, 2021. The minimum temperature forecast from February 11 to February 15 (during the Spring Festival) was predicted to be -2 degrees Celsius, thereby concluding that it would be the coldest Spring Festival in Guangdong province.

To begin with, we searched several official weather release platforms such as the CMA, Central Meteorological Observatory, and Weather China but found no such prediction about the “Coldest Spring Festival,” although there were some low temperature warnings.

Thereafter, we collected the 40-day weather forecast data of Guangdong province from the Weather China website and also collected the temperature data of 21 prefecture-level cities in Guangdong province from January 23 to February 17, 2021 (data source: CMA, the update time is 18:00 on Jan. 12, 2021). We found that the forecast data and historical average temperature data published by the National Meteorological Administration are quite different from the data indicated in the claim. According to the data from the CMA, we calculated that the average temperature in 21 cities in Guangdong province was expected to be between 11.9°C and 20.2°C from January 23 to February 17, 2021. The average temperature from 11th to 15th (during the period of Spring Festival) would be between 12.7°C and 20.4°C. Not only will the temperature not drop below zero degrees Celsius, but it will also be higher than the historical average temperature (11.3°C-17.0°C). The average low temperature forecast for 21 cities in the province on New Year’s Eve (Feb. 11, 2021), was 12.7°C. For the temperature during the Spring Festival in Guangdong province, the prediction data of the CMA is compared with the data in the claim. It can be seen that the temperature prediction data in the claim does not come from the CMA. The forecasts and historical data of CMA indicate that “the coldest Spring Festival in the history of Guangdong province” and “the temperature drops below zero degrees Celsius on New Year’s Eve” are both false.

A comparison between the temperature prediction (maximum) around Spring Festival in Guangdong province in 2021 by the CMA and the prediction by the claim.

A comparison between the temperature prediction (minimum) around Spring Festival in Guangdong province in 2021 by the CMA and the prediction by the claim.

In response to the circulation of the post predicting the weather, on several platforms, the director of Hong Kong Observatory, Cheng Cho-ming, shared a post on his Facebook page (dated Jan. 11, 2021), denying the authenticity of the post. He pointed out that it is impossible that the highest temperature on Feb. 11 is 7°C, and the very next day the lowest temperature is 13°C where exists a 6-degree gap. According to a report on “Hong Kong 01”, Mr. Lee Kwok-lun, the Senior Scientific Director of the Hong Kong Observatory, explained that in the actual temperature forecast, the forecasted temperature ranges for two consecutive days should overlap. However, the data cited in the claim shows that there is no overlap. Therefore, there are obvious scientific mistakes, which also proves that there is a problem with the source of the temperature forecast data.

A screenshot of Cheng Cho-ming’s Facebook post.

On January 14, 2021, the Guangdong Provincial Meteorological Public Service Centre’s official Weibo page, “Guangdong Weather,” made a statement. The statement pointed out that “the lack of scientific basis and the analysis of monthly climate prediction show that the possibility of the coldest Spring Festival is low.” Regarding the technical aspects of weather forecasting, the Guangdong Provincial Meteorological Public Service Center explained that the accuracy of weather prediction exceeding an 11-day time span will be much lower than that within the 11-day range. The longer the time span exceeds, the more complex it becomes to control factors influencing temperature and precipitation, which will significantly affect the forecast accuracy.

A screenshot of a Weibo post from Guangdong Provincial Meteorological Public Service Center’s official Weibo account.

In fact, there have been similar rumours before. In 2017, a message circulated on the internet that the Hong Kong Observatory’s predicted that the Lunar New Year period may be the coldest in history, and listed daily weather forecasts, highest and lowest temperatures. Subsequently, the Hong Kong Observatory clarified in the article “The rumors are coming again, please be careful!”