Why Are My Joints Swelling When It's Hot Out?

If you’ve noticed that your fingers, knees, or ankles feel more swollen or stiff during hot weather, you’re not alone.

Our Interventional Pain and Regenerative Medicine Specialists (IPRMS) team in Arlington, Virginia, can help. Let’s break down why joints swell in warm weather, when it’s normal, and when it might be a sign to check in with your doctor.

Heat and your joints

There are many causes of joint swelling when it’s hot outside, including:

1. Fluid retention

High temperatures cause your body to retain more fluid. This is your body's way of staying hydrated and regulating internal temperature.

Unfortunately, that extra fluid can sometimes pool in the soft tissues around your joints, causing noticeable swelling.

2. Blood vessel expansion

Heat causes vasodilation, a fancy word meaning your blood vessels expand. While this helps cool you down, it can also let more fluid leak into surrounding tissues, especially in your hands, feet, and knees.

3. Inflammatory conditions

Hot weather can sometimes worsen inflammation in people with conditions like arthritis, lupus, or gout. Even slight dehydration can make joint lubrication less effective, leading to more swelling and pain.

4. Physical activity in heat

Summer often encourages more activity—beach days, hikes, sports—which can put extra strain on joints. Combine that with heat-related swelling, and you might really feel the difference.

Tips to reduce swelling

Follow these tips to reduce swelling when it’s hot:

Stay hydrated

Water helps flush out excess sodium and keeps tissues healthy.

Cool down

Use fans, AC, cool showers, or cold compresses on swollen areas.

Elevate your limbs

Prop up swollen legs, arms, or hands to encourage fluid to drain.

Wear compression gear

Light compression socks or sleeves can help manage swelling.

Avoid excess salt

High-sodium foods can worsen fluid retention. Avoid liberal use of the saltshaker and check labels for sodium content.

Pace yourself

Don’t overexert in the heat. Rest often, especially if you notice swelling starting.

Should I continue exercising when it’s hot out?

Most mild swelling from heat is harmless and resolves with rest and cooling down. But if swelling is severe, painful, or doesn't go away, it’s smart to check with your IPRMS provider.

Some people with arthritis report flares in both extreme heat and extreme cold. Changes in barometric pressure, humidity, and personal hydration levels all play a role.

However, we don’t recommend you stop exercising or participating in other outdoor activities when it’s hot. Instead, modify your routine by exercising early in the morning or later in the evening when it's cooler.

Listen to your body. For instance, if your joints swell every time you go for a run, try switching to lower-impact activities like swimming. These are easier on your joints and can help reduce your risk of heat-related illness.

Schedule a visit or seek urgent medical care if:

• Swelling is severe or sudden
• Pain is intense or disabling
• Swelling lasts more than a few days
• You notice redness, heat, or fever (could suggest infection)

How a pain management specialist can help

If swollen joints affect your daily life, a pain management specialist can offer targeted relief via a thorough assessment that identifies the cause of the symptoms.

Schedule a visit at IPRMS today by calling the office or requesting an appointment online.