How to know if a heat wave is coming

water to beat the heat

In summer the frequency and intensity of heat waves increase. In addition, the effects of climate change and the increase in the greenhouse effect and heat waves are becoming more dangerous and intense. many people wonder how to know if a heat wave is coming to prepare for it.

In this article we are going to tell you how to know if a heat wave is coming, what its characteristics are and what you should do to protect yourself from them.

What is a heatwave

how to know if a heat wave is coming

The first thing is to know how to correctly identify what a heat wave is in order to prepare for it. A heat wave is a meteorological phenomenon characterized by a significant and prolonged increase in temperatures in a specific region. During a heat wave, atmospheric conditions generate an accumulation of heat, which can cause temperatures to reach abnormally high levels for that area and period of the year.

This phenomenon is usually caused by various reasons, such as the presence of high atmospheric pressures, the lack of cooling winds, and the intensification of the greenhouse effect due to greenhouse gas emissions. Densely populated urban areas can often experience even higher temperatures due to the phenomenon known as “urban heat island”, where urban surfaces absorb and release heat more efficiently than surrounding rural areas.

Heat waves can have significant effects on human health and the environment. High temperatures can increase the risk of heat-related illnesses such as heat stroke and dehydration, especially in vulnerable groups such as young children, the elderly and people with pre-existing health problems. In addition, heat waves can also aggravate air quality due to increased formation of tropospheric ozone and fine particles, which can negatively affect people with respiratory conditions.

How to know if a heat wave is coming

how to know if a heat wave is coming to protect yourself

Gauging stations are a key tool in understanding if we are being overwhelmed by heat waves. For this task, Aemet has 137 specific sites, 6 of which are located in the Canary Islands, and have sequences long enough to calculate percentiles and are evenly distributed throughout Spain.

To know if a heat wave is coming, you have to go through three processes. In the first process, at least three consecutive days of maximum temperature equal to or higher than the number determined by the threshold are obtained from the weather station. Then the warm days are identified, considering those days in which at least 10% of the sites considered are within one of the warm events of the first phase.

Finally, the heat wave is located, which will combine the previous characteristics. It is important to note that when two heat waves are separated by a single day, they will be considered as one heat wave.

Likewise, the data for the Canary Islands are processed independently because only six stations are used, one of which was enough to record a warm event to be considered a heat wave.

To determine the area affected by a heat wave, the dates on which heat waves occur in most provinces are determined. Likewise, a province is considered to be experiencing a wave when one of its seasons is in a "warm period", that is, "Not enough to exceed the 'threshold temperature' over time."

In terms of magnitude, one must first identify the stations with “warm days” and then take the average maximum air temperature on the hottest day. That number will be the maximum temperature of the wave. A wave anomaly, for its part, corresponds to the average of all the anomalies relative to a threshold.

More heat waves due to climate change

man pouring water

From these data, Aemet knows that 2017 was the year with the most heat waves, with five of them totaling 25 days. 2015 was the longest heat wave year with 26 days, while 2012 was the longest heat wave year, covering 40 provinces.

In the Canary Islands, 1976 had a total of 25 days of heat waves, the longest heat wave being 14 days. It should be noted that the number of heat waves has not stagnated in recent years, but rather has increased. As the summer of 2020 drew to a close, Aemet released its decades-long heat wave record, explaining that there were 23 heat waves between 2011 and 2020, six more than in the previous decade.

The number of days has also increased in the last decade, from the usual six to 14 days.. The same is true for the anomaly, with the anomalous temperature over the past decade 0,1°C above the previous record for the decade between 1981 and 1990.

The only value not exceeded for the decade 2011-2020 is that of the affected provinces, although by a small margin. In this sense, the Aemet pointed out that the average number of provinces affected during the decade was 22, compared to 23 between 1981 and 1990.

Experts have determined that heat waves have become more frequent and intense due to rising global temperatures, which have risen 1,2°C since pre-industrial times, according to the World Meteorological Organization (WMO).

“As global temperatures rise due to greenhouse gas concentrations, heat waves are becoming more frequent and intense. We also see that they start earlier and end later, causing increasing damage to human health,” Omar Baddour, Director of WMO's Climate Policy and Monitoring Division.

Climate-related risks to health, livelihoods, food security, water supply, human security and economic growth will increase with global warming of 1,5°C and will increase further with global warming of 2°C. Limiting warming to 1,5°C instead of 2°C could result in 420 million fewer people experiencing severe heat waves.

I hope that with this information you can learn more about how to know if a heat wave is coming and its characteristics.


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