Extreme heat and humidity are expected in Howard County this weekend, as the National Oceanic and Atmospheric Administration's heat index predicts temperatures as high as 105 degrees.Forecasts for this weekend in Howard County begin with temperatures in the mid- to high-90s Friday morning, possibly reaching 100 degrees Friday afternoon.As high temperatures set in, Howard County officials urge residents to stay hydrated and take precautions when outside. The county has provided the following tips to stay safe in hot weather:• Never leave children or pets unattended in a parked car or other hot environment.• Drink water and caffeine-free liquids. Alcoholic beverages do not keep you hydrated.• Wear light-colored, light-weight, loose-fitting clothing, a hat and sunscreen.• Take frequent rest breaks in air conditioned or shaded environments• Check on elderly friends, family and neighbors.Health concerns are also a significant factor in heat waves, including extreme weakness, muscle cramps, nausea, headache, possible vomiting or fainting and dry red skin. Howard County's 50+ Centers and library branches offer a cool environment, county officials said, during normal hours of operation.It is only expected to get hotter from Saturday through Monday."Any one of those three days, we could hit 100 degrees," said Kevin Witt, a meteorologist with the National Weather Service's Baltimore/Washington forecast office."With added sunshine, you're going to have temperatures soar rather quickly," Witt said.Highs are forecast in the mid- to upper-90s Saturday, Sunday and Monday, and it's hard to predict which will be the hottest, he said.Hot, dry air is forecast to remain over the region for that period, with an unusual pattern expected in which high pressure is present from the ground to the upper levels of the atmosphere some 60,000 feet up. That means lots of clear skies and dry air.For information about the 50+ Centers, go to Howard County's website at www.howardcountymd.gov. Information on Howard County Library System locations and hours of operation is available at hclibrary.org—Baltimore Sun reporter Scott Dance contributed to this story