(CNN) — As the United States celebrates its 250th birthday, firework celebrations are expected to bring more pomp and circumstance than ever before. But with bigger festivities and an oppressive heat ...

(CNN) — Wildfires are expected to bring unhealthy air to more than 120 million people this weekend, but the smoke and its toxic particles may not always be clearly visible. Some skylines are shrouded ...

(CNN) — Thick, choking plumes of smoke from wildfires in Canada are pouring into major cities across the Midwest, Northeast and mid-Atlantic, bringing dangerous air quality to more than 100 million ...

(CNN) — Drenching storms rolled over the flood-ravaged Midwest for a sixth day early Friday, bringing more rain to areas where severe flooding has already forced hundreds of people from their homes ...

(CNN) — An already-strong El Niño just turned super as the phenomenon crosses into unprecedented territory. The natural climate cycle has been strengthening at a breakneck pace since it was first ...