Warm weather causes blood vessels to expand slightly to help regulate body temperature. This natural process can make veins stand out more than usual.
When to Pay Attention
Although visible veins are usually harmless, you may want to consult a healthcare professional if you notice:
Sudden swelling or pain
Hard or tender veins
Skin color changes near the veins
In some situations, these symptoms may be related to conditions such as Varicose Veins or Deep Vein Thrombosis.
Conclusion
Visible veins in the hands are often a normal part of how the body works, especially with aging, exercise, or lower body fat. Most of the time, they are simply a sign of healthy circulation rather than a cause for concern.w
Your body shows many small clues about how it functions—sometimes even through the veins beneath your skin. 
