If you wait until you're thirsty, it's too late.

Thirst is just one symptom of dehydration, but you shouldn't wait until you're parched to drink water.

Although staying adequately hydrated is something to be mindful of all year long, it should be especially top of mind in the summer.

Here's what you need to know about staying hydrated — no matter how hot it is outside:

n There's more to dehydration than you might think.

In addition to increased thirst, dehydration has other common symptoms including dark urine, dry skin, headaches and muscle cramps. In severe but rare cases, symptoms of dehydration can include convulsions and even delirium.

n It can take time for dehydration to settle in.

After spending time outside on a hot day, it might seem obvious to get a drink, but it might take longer for dehydration to settle in.

In some cases, dehydration can happen hours or even days later.

n It doesn't need to be hot outside for someone to become dehydrated.

The summer heat plays a role in dehydration, but it doesn't take triple-digit temperatures to reach a breaking point. Other weather conditions — such as humidity levels and dew points also play a role in how much someone sweats.

When it's muggy outside and humidity and dew points are high, someone might sweat more even if temperatures are relatively mild.

n There's no magic number on the amount of water to drink.

When it comes to how much water to drink per day, experts often cite the 8x8 rule: eight 8-ounce glasses per day. But everybody is different, so some people might need more and others less.

n It takes more than just water to stay hydrated.

Water is great for staying hydrated, but that's not all the body needs. To stay optimally hydrated, the body needs a mix of water and electrolytes.

n Hydrate: Drink plenty of water during the day, especially if you are engaged in any strenuous activity. Sports drinks are a good choice if you're exercising or working in hot conditions, but water is a good way to hydrate as well.

n Ventilate: Stay in a place where there is plenty of air circulating to keep your body cool. If you are indoors and don't have access to air conditioning, open windows and use a fan.

n Cover up: Wear light-colored and loose-fitting clothing to avoid absorbing the sun's light and trapping heat. Wear a hat to shield yourself from the sun, but once you feel yourself getting warm, remove any items covering your head that can trap heat close to your body.

n Limit activity: Heatstroke can occur in less than an hour when you are participating in strenuous activity during a hot day. If you feel yourself getting hot or lightheaded, stop your activity and rest in a cool place out of the sun.

n Check on loved ones: The elderly are especially vulnerable to heat-related emergencies. Many elderly residents are not aware of how hot it may get in their residence. Call on older friends and family members regularly to assure they are doing OK.