Understanding the Impact of Fluctuating Summer Temperatures
June marks the start of meteorological summer, but after last week’s heatwave, this week is expected to bring cooler and wetter conditions. The Met Office has predicted spells of rain, possible thunderstorms, and some strengthening winds throughout much of the week. These dramatic weather changes can leave many people feeling unsettled, both mentally and physically.
Dr Lucy Hooper, a London-based GP and co-founder of Coyne Medical, explains that one of the main challenges is the difficulty the body faces in acclimatising to frequent temperature swings. “In Britain, we experience hot spells followed by cold weather, which means we don’t get the chance to fully acclimatise to the weather,” says Hooper. 
“In hotter countries, people adjust their behaviour and fluid intake, and their bodies learn to adapt. However, because we frequently face sudden weather changes in the UK, we don’t build up that tolerance. It takes around seven to 14 days to really acclimatise to hotter climates, but we’re seeing weather changes on a daily basis.”
Hooper warns that increasingly unpredictable summers, characterised by alternating periods of heat and cool weather, may be more disruptive than sustained warm spells. “We’re likely to have summers where it’s hot, cold, hot, and cold again. This can be more destabilising than just having four to six weeks of really hot weather because your body is constantly trying to find a new regulation and balance, only for the environment to change again.”
Four Ways Fluctuating Temperatures Affect Wellbeing
1. Sleep
Warm weather has a significant impact on our bodies, particularly on sleep. “Even moderate increases in temperature can make us lose out on some of the restorative sleep stages, which can have a big impact on our overall health and wellbeing,” says Hooper.
2. Mood
Many people associate Seasonal Affective Disorder (SAD) with the colder, winter months, but it can also affect people in the summer. “Lots of data shows that some people experience SAD in the summer, and rising temperatures can also influence things like aggression,” says Hooper. “People often become more stressed in the heat, and there seems to be a link between rising temperatures and increasing crime rates and domestic violence rates.”
3. Immune System
“Heat can definitely impact the immune system,” says Hooper. “You get more inflammatory signals and stress responses happening in the body, and then after a while, if that continues, the body often stops responding to those stress signals as a way of conserving energy.”
“This is why we think that if you’re in a lot of heat exposure, your immune system might not respond as well as it usually does. When the weather gets cooler, there’s less stress on the body, giving an opportunity for your immune system to recover. However, responses to heat stress are not something that happens instantly as the temperature drops. It takes time for our body to recover from that stress, and the impact is still felt for a little while later.”
4. Brain Fog
“Hormone changes, such as cortisol and serotonin, in hot weather can affect our brain function in terms of memory, decision-making, and energy levels,” says Hooper. “Even once the temperature is lower, people still seem to have some response to that. For example, brain function doesn’t go back to people’s normal baseline straight away.”
“This is especially the case in middle-aged and older adults, where there seems to often be some prolonged dysfunction of their brain and neurological function.”
5. Cardiovascular System
“In hot weather, your heart rate goes up, your blood is pumping more, and there’s more blood flow around the body, which can put more strain on the heart,” says Hooper. “Although that should all be relieved when temperatures fall, it doesn’t change immediately, and there may still be some strain felt after hot spells.”
Tips to Minimise the Impact
There are several things you can do to counteract these effects. “Good sleep is a big thing to prioritise,” advises Hooper. “Do what you can practically to help that happen, such as keeping your bedroom cool.”
She also recommends thinking about how the fluctuations in temperature might be impacting your wellbeing. “If you are feeling more stressed or irritable or angry than usual, maybe there are some self-care things you can do to take care of yourself so it doesn’t start negatively impacting you and your relationships.”
Staying hydrated is also crucial. “Keeping hydrated is a really important and relatively simple thing that we can do,” recommends Hooper. “In addition, make sure that you are still getting out and seeing people. Keeping to your regular routines as much as possible can also help you stay feeling well.”
