AUSTIN (KXAN) — Typically, a wet spring and beginning of summer lead to fewer 100º high temperatures in July and August.
High soil moisture from rainfall can help to moderate summer heat for weeks or months thereafter, keeping high temperatures during the drier months of summer several degrees milder than they would otherwise be.
Camp Mabry recorded nearly double its average rainfall from April through June, tallying 19.25″ versus an average of 10.86″. While this did stave off 100º heat in Austin until July 14, we have since then tallied 29 100º days, and 16 of those have been consecutive. If our 7-day forecast verifies, we may tally 23 consecutive 100º days by Tuesday next week — our second-longest heat wave in recorded history.
Quick whiplash back to dry weather is certainly to blame. Camp Mabry has only had 1 day with measurable rainfall out of the last 43, flash-drying our soil and allowing afternoon highs to soar higher. But could there be something else at work?
As the world’s climate changes due to human activity, Austin is averaging more 100º days each summer. The 30-year average is close to 13 triple-digit days per year, but you can see how sharply that number has increased since 1970 on this Climate Central study below.
Record heat in Austin used to occur at relatively the same frequency as record cold. In other words, there were equal extremes on both sides of the spectrum. These days, record heat is far-outpacing record cold as the climate warms.
While it takes weeks or months after the fact to scientifically diagnose any specific weather event to climate change, an average summertime high temperature of 98º in Austin makes our 100º-day count especially sensitive to the warmer average temperatures we are observing each decade.