ALBANY, N.Y. (NEWS10) — A sudden change in temperature can be potentially dangerous. Ahead of a forecast heatwave, one local doctor warns that, with people not used to extreme temperatures, there is a risk for heat exhaustion, especially among vulnerable groups.

Temperatures are expected to climb into the 90s on Saturday. Dr. Robert Brewer, associate director of emergency medicine at St. Peter’s Hospital has a few reminders to keep cool. “People aren’t used to this heat so they’ll get overheated very quickly,” he explained. “Making sure when you’re active, you’re sweating. Sweating is a natural mechanism to cool the body down. If you’re not sweating, that could be a big problem really quickly.”

Staying hydrated with water or sports drinks with electrolytes will help your body stay cool. The heat exhaustion symptoms to watch out for include dizziness, fatigue, and nausea. Dr. Brewer added, “If you start feeling that way you need to remove yourself, sit in a shaded area or air-conditioned building.”

The group he is most concerned about during extreme heat is the elderly, who have chronic medical problems. Dr. Brewer explained they are at a much greater risk for both heat exhaustion and heatstroke.

If your plans include spending time outdoors this weekend the doctor recommended against some popular drink choices. “Excessive alcohol can wash out electrolytes not hydrating you, you feel like you’re drinking a lot but not hydrating from it. Caffeinated beverages are another one, like energy drinks.”

Ahead of Saturday’s heat Rensselaer and Schenectady Counties are opening up cooling stations for the public.