After experiencing one of the hottest spells of weather ever recorded in June, many people across the UK have welcomed the recent drop in temperatures. Last week saw new June temperature records broken on three consecutive days, with highs reaching 37.3°C in parts of England. Whilst this week has brought cooler conditions and some much-needed rain, forecasters suggest that another period of hot weather could return as we move into early July.
Whether temperatures remain moderate or another heatwave develops, changing weather conditions can have a noticeable effect on your eyes. During warmer periods, many people experience dry, irritated or watery eyes, increased sensitivity to bright sunlight, blurred vision, or discomfort when wearing contact lenses. These symptoms are often dismissed as a normal consequence of the weather, but they are usually the result of changes occurring on the surface of the eye.
As a Consultant Ophthalmologist specialising in cataract and glaucoma, I frequently see patients whose eye symptoms become more noticeable during periods of hot weather. Heat, ultraviolet (UV) radiation, dehydration, pollen and air conditioning can all affect the delicate tear film that protects the eye, leading to irritation and visual discomfort. For some individuals, particularly those with dry eye disease, cataracts or existing eye conditions, these symptoms can become increasingly troublesome.
Understanding how hot weather affects your eyes can help you recognise the symptoms early, take simple preventative measures, and know when it is appropriate to seek professional advice.
Why Does Hot Weather Affect Your Eyes?
The surface of the eye is protected by an incredibly delicate layer of tears known as the tear film. Although only microscopic in thickness, this transparent layer performs several essential functions. It lubricates the eye, protects against bacteria and debris, supplies oxygen and nutrients to the cornea, and creates a smooth optical surface that allows light to focus correctly.
The tear film is made up of three layers—an oily outer layer that slows evaporation, a watery middle layer that provides moisture, and a mucus layer that helps tears spread evenly across the eye. When these layers remain balanced, your eyes feel comfortable and your vision remains clear.
During periods of hot weather, however, this balance can quickly be disrupted.
Higher temperatures, lower humidity, warm winds and prolonged exposure to sunlight all increase the rate at which tears evaporate from the eye’s surface. Many people then move between outdoor heat and air-conditioned buildings or vehicles, where dry circulating air causes further evaporation.
As the tear film becomes unstable, the surface of the eye begins to dry out. This can lead to irritation, fluctuating vision and increasing discomfort throughout the day.
People who already suffer from dry eye disease, meibomian gland dysfunction, blepharitis or autoimmune conditions often notice that their symptoms become significantly worse during a heatwave.
Why Do My Eyes Feel Dry During Hot Weather?
Dry eye is one of the most common conditions seen by ophthalmologists, and summer weather often makes the symptoms considerably more noticeable.
Patients frequently describe their eyes as feeling:
- Dry or gritty
- Burning or stinging
- Tired or heavy
- Red and irritated
- Sensitive to bright light
- Uncomfortable when reading or using digital screens
Many people also notice that their vision seems blurred at times but then clears after blinking.
This happens because the tear film forms part of the eye’s focusing system. When the tear film becomes irregular through evaporation, light entering the eye is scattered before it reaches the retina. As a result, vision may fluctuate throughout the day, particularly during prolonged reading, computer use or driving.
One factor that many people overlook is dehydration. During hot weather, the body naturally loses more fluid through perspiration. If you are not replacing these fluids, tear production can reduce, making symptoms worse.
Why Are My Eyes Watering If They’re Dry?
One of the most common misconceptions I hear from patients is:
“My eyes can’t be dry because they’re constantly watering.”
In reality, excessive watering is often a sign of dry eye disease.
When the eye becomes excessively dry or irritated, the surface sends an emergency signal to the tear glands to produce large quantities of reflex tears.
Unfortunately, these tears are different from normal healthy tears.
They are mostly water and lack the balanced mixture of oils and mucus required to properly lubricate the eye. Instead of remaining on the eye’s surface, they quickly overflow onto the cheeks.
The result is a frustrating cycle where your eyes continue to water but never actually feel comfortable.
Understanding this process is important because many people mistakenly believe watering means they have “too many tears”, when in fact they may require treatment for dry eye disease.
Bright Sunlight, Glare and Cataracts
Another common complaint during periods of bright sunshine is glare.
Glare occurs when intense sunlight scatters inside the eye, reducing contrast and making everyday activities more difficult.
Many people notice this whilst:
- Driving
- Reading road signs
- Walking outdoors
- Playing golf or other outdoor sports
- Reading in bright sunlight
Patients with cataracts often experience these symptoms more severely.
A cataract develops when the eye’s natural lens gradually becomes cloudy. Instead of allowing light to pass cleanly through to the retina, the cloudy lens scatters incoming light in multiple directions.
During bright summer days, this scattered light becomes much more noticeable, causing increased glare, reduced contrast sensitivity and greater sensitivity to sunlight.
Many patients tell me they are comfortable driving on dull winter days but struggle considerably during bright sunshine.
Others notice that colours appear less vibrant or that they find themselves avoiding driving because the glare has become uncomfortable.
It is important to remember that sunglasses can improve comfort by reducing glare, but they do not treat the cataract itself. If glare begins affecting your daily activities or confidence behind the wheel, it may be an appropriate time to consider a comprehensive cataract assessment.
Contact Lenses During Hot Weather
Hot weather can present additional challenges for people who wear contact lenses. During a heatwave, increased tear evaporation and dehydration can reduce the amount of moisture available on the surface of the eye, making contact lenses feel dry, uncomfortable, or as though they are sticking to the eye.
Many patients also notice that they are less able to tolerate their contact lenses for the same length of time they normally would. This is because the tear film, which helps the lens move comfortably across the surface of the eye, becomes less stable as it evaporates more quickly in warm conditions.
If you wear contact lenses during periods of hot weather, it is important to stay well hydrated, avoid wearing lenses for longer than recommended, and use preservative-free lubricating eye drops if appropriate for your type of lenses.
Swimming with contact lenses should also be avoided wherever possible. Swimming pools, lakes, rivers and even seawater can contain bacteria and microscopic organisms that may become trapped beneath the lens. One rare but serious infection, Acanthamoeba keratitis, can threaten sight and may require prolonged treatment. If you intend to swim, prescription swimming goggles provide a much safer alternative.
Hay Fever and Summer Allergies
Summer is also synonymous with hay fever, and while most people associate allergies with sneezing and a runny nose, the eyes are often one of the first areas affected.
Pollen can trigger inflammation of the delicate tissues covering the eye, resulting in itching, redness, watering and swollen eyelids. These symptoms are often made worse by hot, dry weather and windy conditions, which increase the amount of pollen circulating in the air.
The instinctive reaction is to rub the eyes. Unfortunately, this often makes matters worse. Rubbing can increase inflammation, irritate the surface of the eye and, over time, may even weaken the cornea in susceptible individuals. For patients with conditions such as keratoconus, repeated eye rubbing is particularly discouraged.
If your symptoms are allergy-related, preservative-free lubricating drops can help wash allergens away from the eye, while antihistamine eye drops may provide additional relief where appropriate. If symptoms are persistent or affecting your vision, a professional assessment is recommended.
Ultraviolet Radiation and Long-Term Eye Health
While dry eyes and glare are often temporary, prolonged exposure to ultraviolet (UV) radiation can have lasting effects on your eyes.
Much like the skin, the eyes absorb ultraviolet light throughout our lifetime. Although the body has natural protective mechanisms, years of cumulative UV exposure have been associated with an increased risk of several eye conditions, including cataracts, pterygium (a growth on the surface of the eye), certain retinal conditions, and damage to the delicate skin surrounding the eyelids.
This damage develops gradually over many years, which means you may not notice any immediate effects after spending time in the sun. However, protecting your eyes today may help reduce the risk of problems later in life.
When choosing sunglasses, they should provide 100% protection against both UVA and UVB rays (UV400). Larger frames or wraparound styles offer additional protection by reducing the amount of sunlight entering from the sides. A wide-brimmed hat can further reduce UV exposure, particularly during the brightest part of the day.
It is worth remembering that ultraviolet radiation penetrates cloud cover. Even on overcast summer days, your eyes remain exposed to UV rays, making eye protection important regardless of whether the sun is clearly visible.
Looking After Your Eyes During a Heatwave
Fortunately, a few simple measures can make a significant difference to your comfort and long-term eye health.
Maintaining good hydration supports healthy tear production and helps reduce symptoms of dry eye. If your eyes regularly feel dry or irritated, preservative-free lubricating eye drops can help stabilise the tear film and improve comfort.
When spending time outdoors, wear sunglasses that provide certified UV protection and consider wearing a wide-brimmed hat for additional shade. If possible, avoid prolonged exposure during the middle of the day when ultraviolet radiation is strongest.
If you spend long periods using computers, tablets or smartphones, remember that we naturally blink less when concentrating on screens. Taking regular breaks and consciously blinking more frequently can help prevent the tear film from evaporating too quickly.
For contact lens wearers, maintaining excellent lens hygiene, avoiding swimming whilst wearing lenses, and allowing your eyes regular breaks from lens wear can all improve comfort during warmer weather.
These simple habits can help keep your eyes healthy, comfortable and well protected throughout the summer.
When Should You Seek Professional Advice?
Although many symptoms associated with hot weather are temporary, persistent or worsening symptoms should never be ignored.
You should arrange an urgent eye examination if you experience:
- A sudden reduction in vision.
- Severe or persistent eye pain.
- Significant redness that does not improve.
- Increasing sensitivity to light.
- Flashes of light or a sudden increase in floaters.
- Persistent blurred vision.
- Any sudden loss of vision.
Prompt assessment is particularly important because many eye conditions respond far better when diagnosed and treated early.
If you have cataracts, glaucoma, diabetes or an existing eye condition, regular eye examinations remain one of the most effective ways to monitor your eye health and preserve your vision.
Final Thoughts
Hot weather places additional demands on the eyes, even in people who have never experienced eye problems before. Dryness, irritation, watery eyes, glare and sensitivity to sunlight are all common complaints during periods of prolonged heat, yet many people simply accept them as an unavoidable part of summer.
In reality, understanding why these symptoms occur allows you to take simple but effective steps to protect your eyes. Staying hydrated, wearing appropriate UV protection, managing allergies, and looking after the tear film can all help maintain comfortable vision throughout the warmer months.
As a Consultant Ophthalmologist, I encourage patients to think of eye care in the same way they think about protecting their skin. The effects of excessive ultraviolet exposure and chronic dryness are often cumulative, meaning the decisions you make today can have a positive impact on your eye health for many years to come.
Need Expert Advice?
If you have noticed increasing glare, dry or watery eyes, discomfort when wearing contact lenses, or changes in your vision during the warmer months, it is always worth seeking professional advice.
Gurjeet Jutley is a Consultant Ophthalmologist specialising in cataract and glaucoma, providing expert diagnosis, treatment and personalised eye care across Oxford, Northampton, Windsor and Murcia (Spain).
Whether you are concerned about dry eye disease, cataracts, glaucoma or another eye condition, expert assessment can provide reassurance and ensure that any underlying problems are identified at the earliest opportunity.
To arrange a consultation or discuss your eye health, please get in touch. Protecting your vision starts with taking the first step.