This year's early bout of heat is likely to blame for the early sightings. The National Weather Service has issued warnings for much of Southeast Texas this week, where an unseasonably intense heat wave is developing. Cities like Houston are expected to hit the mid to upper 90s this week, possibly breaking temperature records for May.

Heat advisories and extreme heat warnings are in effect west of Houston this week as an unusually early heat wave takes hold. What do these heat alerts mean?

The Texas-Mexico border is scorching under a record-setting heat wave, with temperatures soaring past 100 degrees, making it Earth's hottest spot today.

Summer temperatures in Central Texas are predicted to break records this week. You can almost feel the heat coming off these photos.

Record-breaking Texas heat threatens millions as forecasts predict nationwide temperature extremes through summer. Learn the risks and how climate changes

Some claim that keeping your garage door cracked keeps your home cooler. Here's what experts say about the popular tip and how to stay cool this year.

In Texas, a large area of the state is expected to experience temperatures up 15 to 25 degrees above normal — into the 90s and 100s in all but a few locations.

US weather forecast predicted a very strong heatwave is coming to many places in the U.S. this week. It is hotter than normal for this time of year and is arriving early, before summer.