In brief: The Gulf tropical disturbance is unlikely to develop, but it will bring some rain to the area tomorrow and Saturday. We have one more shot at 100 today before a brief break. More 100 chances return next week. Today we also dive into Bush Airport and talk about why it seemed to be such an outlier on Tuesday.

First, the tropics

Let’s start quickly this morning with the tropics and on this disturbance we have moving across the Gulf today and into our region tomorrow. There continues to be little to no chance of development with this. For Greater Houston, that means an increase in rain chances tomorrow and Saturday. And even that should be manageable.

Now, how much rain? Well, Friday will be interesting. It could go one of two ways I think. The first way? The disturbance approaches Texas and we get a solid rain shield offshore, so coastal areas see a fair bit of rain in the morning, with inland areas seeing just a few scattered afternoon thunderstorms. Alternatively, we see a small bit of rain in the morning at the coast and then more numerous showers and afternoon thunderstorms moving southeast to northwest across the region. I am leaning heavily toward the coastal rain outcome, where inland areas see some scattered storms but nothing too widespread. This means folks in Galveston could easily see a couple inches of rain, and more numerous showers and storms may push across Brazoria, Galveston, and Chambers Counties.

On Saturday, we’ll probably see a repeat, except I think storms could be more numerous across the entire region. As we’ve been saying, it should not be a total washout, but you’ll want to have some rain plans in place on both Friday and Saturday if you’re planning outdoor activities.

Rain totals will be on the order of probably 1 to 2 inches at the coast and a gradual trailing off of rain inland down to about a half-inch to inch inside the 610 Loop and less than that farther inland on average. Some areas may see little to no rain. Other isolated pockets, especially south and east of Houston could see 3 to 4 inches of rain.

Next, the heat

We hit 99 degrees yesterday, and we will make another run for 99 or 100 today probably. With clouds and showers around, Friday and Saturday should be substantially less hot. But look for the heat to return Sunday or Monday, and we will be making another run at 100 degrees by Tuesday or Wednesday.

Is the IAH thermometer rigged?

The fun thing about weather is that no matter where you live, if something looks the slightest bit suspicious, people start weighing in with lukewarm and hot takes about why there’s something wrong with a temperature sensor, someone has an agenda and is purposefully fudging data, and on and on. One of my favorites is when Washington, DC gets snow, virtually the entire city gets mad at whoever measures the snow at Reagan Airport because it is obviously too low. In Philadelphia, you get the opposite, the snow totals almost always get yelled at by people for being inflated.

Well, we’ve got ourselves a fun game of this happening in Houston now. On Tuesday, when IAH hit 100 degrees, many people were convinced it made no sense.

And, honestly, looking at that map above, I get it. IAH does stand out. Out of an abundance of caution, the NWS sent their electronics technician out to look at the thermometer at IAH. It was fine. It was reading where it should have been, and there have not been any recent changes near the thermometer. Turns out, it’s just hot at IAH. If you look at the high temperatures on Tuesday from a number of additional weather stations, filtered for most of the clearly bogus values (50s, 110s), you’ll see multiple spots hit 100 degrees.

I’m not going to say that each of these weather sensors is sited perfectly or calibrated perfectly, but based on what I saw from sensors that I trust on Tuesday, I would have expected IAH to top off around 98-99 degrees. So, 100 doesn’t exactly shock me. But it’s definitely at the top end of temps for our area.

So, what is the deal with IAH, and can we trust it as a long-term indicator of our climate? It’s a complex and complicated question to answer. In most cities, historical data did move from essentially the center of town “back in the day” to airports. Official readings are now almost always taken at airports, where no one actually lives, of course.

A few places are unique or have complexities: Think Central Park in New York City; not an airport and a good, long historical data record. In Austin, you get to choose from Bergstrom Airport or Camp Mabry, two locations that can be very, very different during certain events. Downtown Los Angeles has also had a checkered history, with a weather station that has now moved 8 times. The linked article is from 2014, when USC housed the official Downtown L.A. sensor. It now sits on the south side of Dodger Stadium. The next time I visit SoCal, I intend to wear an Altuve jersey, go stand by it, and boo it. When stations like this move, there’s a process called “threading” that occurs. This process is by no means perfect, but it does a fairly good job of ensuring that station discontinuities are accounted for and the extremes we’re measuring against historically are as unified and realistic as possible.

Is IAH a reliable indicator of Houston’s weather history? Ten people will have ten opinions on this, but the reality is that it’s not really any worse than any other spot in the area. Houston is constantly evolving, growing, and changing. IAH isn’t perfect, but I think the important takeaway would be that there’s a difference between being representative of where people live versus being representative of reality at a given point. IAH isn’t a reliable indicator of every neighborhood’s weather history in Houston. But it is reliable as a location for our climatology today. In other words, compare IAH to IAH, not IAH to elsewhere. IAH hit 100 on Tuesday. Compared to previous records at IAH, it was one degree shy of a record high. That doesn’t mean that Sunnyside was 1 degree shy of a record. Or Sheldon was 1 degree shy of a record. IAH was. And since our official records are kept there, “Houston” was. You could make a similar argument about DFW Airport, which keeps Dallas’s official records or O’Hare in Chicago or Logan Airport in Boston.

Going back to the 100 on Tuesday, one of the key reasons for it may have been the lower humidity we saw that bubbled up in a pocket of the city. We can assess that with dewpoint values, as seen below. Also, IAH had 42% relative humidity at 3 PM, right around when it hit 100 degrees, which was one of the lowest relative humidity values in the city at that time.

Drier air heats up more efficiently than more humid air, and when you have an air mass this hot, it doesn’t take a massive change in humidity to lead to a somewhat outsized change in temperature. Bottom line? It seems that a localized pocket of low humidity impacted the area near the airport. When combined with the already generally hot location of IAH, it led to a bump to 100 degrees on Tuesday, when most other locations were more like 96 to 98 degrees.

Does this settle the debate? Never. Everyone will still have opinions on this. Weather is a bit like sports in that regard, I guess. But when thinking of IAH, it’s a microcosm of all the things influencing our history here: Urban heat island, sprawl, a warming Gulf, and climate change all playing roles. But we wanted to share some of the plausible reasons why it happened, as well as add some color on IAH. Not perfect, but it’s what we’ve got.

In brief: We should see two more days of some of summer’s hottest weather to date before a tropical disturbance brings clouds and rain chances Friday and Saturday. We start to heat back up again next week with another round of 100° risk possibly beginning on Tuesday.

Yesterday bested Monday for Houston’s hottest day of summer. We officially hit 100 degrees for the first time since August 22nd of last year. Congratulations. This is our 4th summer in a row with at least one 100 degree day. 2021 had none. For real.

Today and Thursday

More heat. More humidity. More ouch. We will probably threaten yesterday’s hottest day of summer record on either or both days.

Rain chances will be at a minimum.

Friday & Saturday

We continue to see plenty of signs that the tropical wave moving across the Gulf will “make landfall” in Southeast Texas on Friday. No development is expected (though the NHC did tag it at 10% yesterday evening). However, it will nudge up our rain chances substantially on both Friday and Saturday, especially near the coast and east of Houston. Rain chances will also spread inland too. But the best chance of some locally heavy rainfall will be south and east.

I’m not sure I would go cancelling outdoor plans just yet. You may still be able to squeak some windows in of drier weather on those days, particularly away from the coast. But stay tuned.

Temperatures will be held back due to clouds. Look for highs in the low-90s at best, possibly upper-80s in a couple spots, especially south and east.

Sunday & Monday

We should transition out of this pattern at the end of the weekend and on Monday. Look for highs to bounce back into the mid-90s or even a bit hotter by Monday.

Tuesday through Thursday

I would expect us to see another round of heat rivaling the hottest of summer beginning next Tuesday. Highs will approach 100 degrees in spots. Rain chances will again be minimal. Or so we think. If the ridge of high pressure over the Plains orients a little further north, it could crack the door to the Gulf open some more. If that happens, we could possibly see more cooling downpours each afternoon. We’ll see. More to come.

In brief: After Houston’s hottest summer day so far, more heat is likely to persist today through Thursday. A tropical disturbance (that will not develop) will bring ample rain and storm chances back to the area Friday and Saturday before we jump right back into the hot stuff next week.

Summer to date in context

Since the weather is pretty cut and dry the next few days, let’s talk briefly about this summer. Officially, yesterday was our hottest day of the year, with a daily average of 89 degrees at Bush Airport, besting the 88.5° we hit 4 times, last on June 21st. But someone messaged us on Instagram recently asking if it was a pretty mild summer so far. “I’ve been able to enjoy the mornings and evenings outside which hasn’t always been the case,” they noted. And, I had to agree! It’s been hot, just as every summer is, but we’ve had enough rain chances (almost daily it seems) to break it up. It’s felt kind of like what would be a typical Houston summer.

And then Lee Corso barged in and said, “Not so fast, my friend.”

Statistically, from June 1st through Sunday, this has been the 7th hottest summer on record to date in Houston. In fact, we’re even a smidge hotter than 2024, though significantly trailing 2022 and 2023 to this point. We have averaged 84.9 degrees officially. This is about a solid 2 degrees warmer than normal. So why has it seemed less intense? In a word, the daytimes. Our daily high temperatures average 19th hottest on record. In other words, although this is one of Houston’s hottest summers on record to date, it hasn’t been that bad during the daytime. So it hasn’t seemed too intense. And on the days that it has been bad, we’ve often had rain showers to punctuate things. However, if you look at nighttime lows? It’s the 3rd warmest summer on record to date, trailing only 2022 and 2023 and only one spot ahead of 2024. Notice a pattern?

So factor it all together: Modestly hot days, punctuated by daily thunderstorms, followed by a bunch of persistently warm nights, and you get the seventh hottest summer to date in Houston that doesn’t feel all that terrible. It’s a weird outcome, but the numbers don’t lie.

Today through Thursday

Look for the heat to keep up the next 2 to 3 days. Each day will probably top off in the mid to upper 90s. I would not be the least bit surprised to see a few spots hit 100 degrees before Thursday is out. Given that this is the hottest weather we’ve had in a month and the hottest of summer, give yourself a little grace out there and take it easy, stay hydrated, check on pets, check on the elderly, and always check the backseat before you lock the car.

Friday and Saturday

The remnants of our old friend, Invest 93L are diving into the Florida Peninsula today. This system will enter the northwest Gulf on Wednesday, track west on Thursday, and it will probably come ashore between Matagorda Bay and Cameron, Louisiana on Friday. No development is expected, as wind shear is too hostile, and dry air is likely available for disruption. But, what it will do is pick up our shower and storm chances to close the week and start the weekend.

We are probably looking at a 40 to 60 percent chance of showers and storms on Friday and Saturday. This will allow high temps to plunge back into the low-90s. With enough clouds and rain, we may only make it to 90 degrees on either day in a few spots. In terms of total rainfall, it will not be uniform, as some areas will see modest amounts or little rain, while a few other locations could pick up 1 to 3 inches of rain, probably east of Houston or closer to the coast it seems right now. More on this tomorrow and Thursday.

Sunday into next week

That disturbance will exit on Sunday, lowering rain chances again. I would expect highs to return to the mid-90s by Sunday and then upper-90s at times next week, as a monster ridge of high pressure sets up over the Southern Plains. We will probably flirt with the hottest weather of summer again for much of next week.

In brief: As we approach our typical peak of summer heat, we’ll be seeing an uptick in temperatures through the week. We should see potentially upper-90s to near 100 in spots by late week before some shower chances re-enter the forecast. Even hotter weather is possible next week.

Houston’s summer heat typically peaks between July 29th and August 12th, when our average high temperatures sits at 96° and our average low temperature is 76 degrees. The actual peak date is probably around August 5th. So, we are nearing the top of the mountain, and this week may prove to include our hottest weather of summer.

Today through Wednesday

We will start the week with heat and humidity that slowly builds. Highs will push into the mid and perhaps upper 90s by midweek. Thunderstorm chances, while not quite zero each day are fairly low. Morning lows are likely to be in the upper 70s.

Thursday and Friday

I have a feeling that Thursday may be the hottest day of the week. And if not, then it will probably be Friday.

The National Weather Service’s experimental HeatRisk product puts our area in high risk on both days, with a strong edge to Thursday right now. Either way, expect some of the hottest weather of summer so far this week.

By the time we get to Friday, we may see showers or thunderstorms re-enter the forecast, depending on the track of a tropical wave in the Gulf. No development is expected, but a similar track to last week’s Invest 93L is possible, which could keep most of the rain to our east again — or a somewhat more southerly track could bring higher rain chances to our area by Friday. Something we’ll watch through the week, but the main takeaway here is that, again, no development is expected.

Weekend and beyond

Once that wave passes, we should sort of resume a typical summer pattern of heat, humidity, and slight daily storm chances in the area. It does appear that a very strong ridge of high pressure in the upper atmosphere is going to establish over the Southern Plains next week.

We may be on the periphery of it enough to get continued shower chances each afternoon, but if this flexes much further, we may see even hotter weather next week, perhaps the hottest of summer. Stay tuned.