Hi brightmoon,
Yes,usually, but they are based on facts that we see here and now. However, sometimes the facts are misinterpreted. On another thread, discussing ice melt, I pointed out how several years ago some climatologists laid claim to the 'fact' that by 2020 the glaciers of Glacier National Park would be gone. Well, here it is 2020, and while they are reduced in size, they are still there and they recently took all the signs down.
Admittedly this isn't a big deal, but it does point out that sometimes the 'theories' don't quite pan out the way they were expected to, even though they were based on facts. While we like to think of ourselves as very, very wise in our endeavors to know all about everything around us, sometimes, especially in forecasts and long ago historical events, there are factors that we don't know to consider that cause us to make erroneous claims.
God bless,
In Christ, ted