In brief: In today’s post we talk about Wet Bulb Globe Temperatures, which are useful at this time of year to help differentiate “hot” weather from “extremely hot” weather you need to avoid being outdoors during. We’re going to see some of the latter this week.

WBGT, and what does it mean for me

There are many ways to talk about heat: high temperatures, the heat index, “extreme” heat warnings, and more. But the most practical (which also, I acknowledge, has the most confusing name) is something called Wet Bulb Globe Temperatures. It takes a lot of factors into account, including temperature, humidity, wind speed, Sun angle and cloud cover to determine the amount of heat stress. It is particularly helpful for determining whether outdoor exercise or work is safe. If you have kids in fall sports or marching band, these temperatures are often used to set practice times.

The confusion comes not just from the name (what the heck is a “wet bulb” anyway?) but also because there are other, similar names. For example, a dry-bulb temperature is the name for an air temperature measured by a standard thermometer in the shade. A wet-bulb temperature involves placing a wet cloth around a thermometer bulb, and it measures both temperature and humidity. Globe temperature measures radiant heat (i.e. sunlight and heat radiating from surfaces such as concrete).

All three of these are factored into a “Wet Bulb Globe Temperature.” So yes, it’s a bit complicated, but WBGTs are the very best way of differentiating between “hot” temperatures and really hot, borderline-unsafe temperatures.

This week we have a sustained stretch of “extreme” heat in terms of WBGTs. We’ve certainly seen hotter, but each day this week from about 1 to 3 pm CT we will experience extreme or very high WBGT conditions. It’s the time of year to take heat warnings safely. We typically see them in July, August, or early September.

Tuesday through Saturday

There is no mystery with our upcoming weather. High temperatures will be about 100 degrees in Houston for the next couple of days, and then push into the low-100s during the Thursday through Saturday period. It will be our hottest weather of the year. Along with the heat we’ll have plenty of humidity, sunshine, and generally light winds that will gust up to about 15 mph during the afternoon hours. Nights will remain warm and sultry. And that’s pretty much it—for most of us this is pretty brutal weather.

Sunday and beyond

High pressure begins to retreat toward the end of this week, and that will open up the possibility that we see some slightly different weather by the end of this weekend, and during the first half of this week. Best case? Daily high temperatures fall back into the mid-90s, and we see some decent daily rain chances. Worst case? We more or less continue the conditions of this week, and keep on trucking with very hot days and full sunshine. We’ll have to see how things play out.

In brief: In today’s post we take stock of the good news, and the bad news about Houston’s weather so far this summer. Also, we look ahead to a blazing hot week. And we do mean blazing. Stay cool, y’all!

First, the good news

There are many ways of defining summer. Meteorologically, it lasts from June 1 through August 31. Practically, in Houston, it runs from mid-May through September. However what’s clear is that we are now a little more than half-way through summer. Plausibly, we are as little as six to eight weeks away from the first cool front of fall.

To date this summer has not been extraordinarily hot; rather we have been pretty much spot-on with normal temperatures for June and most of July. And finally, the greater Houston area (and much of the state of Texas) are drought free. This is often the season when droughts are typically blooming, but not this year. So all in all, so far this summer, we are doing pretty well.

Now, the bad news

I started this post with some positivity because, for most people, we are about to begin the grimmest time of year. August, the region’s hottest month, is days away. The next two weeks are, historically, the very warmest period for the city. And we are expected to have warmer than normal temperatures for at least the next week. So yeah, prepare to sweat.

The other thing is that we are nearing the height of hurricane season. For Texas, the peak lasts from mid-August through late September. So it is about time to buckle up. Crazily, the first two named storms of the season—Arthur and Bertha—both passed over the greater Houston area. Neither had super significant effects locally, but both were rainmakers for some parts of Texas and Louisiana. I have to tell you, we don’t want named storms hitting near us in August or September, when stronger storms are likely. Fortunately the next week or two, at least, things look quiet in the Gulf.

Finally, a word of thanks

I rely on a lot of people here at Space City Weather. We also have a great, long-term partner in Reliant who helps us keep the lights on. But most important of all is Matt Lanza, who stepped in last week to handle the site while I was on vacation, and wound up covering a low-end tropical storm. I take one week a year fully off from the site to recharge, and it happened to be last week. Thankfully we all survived and I’m back and in the saddle, ready for whatever the coming weeks will bring. Hopefully nothing of consequence!

Monday through Friday

This week is going to be downright hot. The reason? High pressure is in place, and at least through the work week it’s not going anywhere. For much of Houston that will mean high temperatures in the vicinity of 100 degrees, with overnight lows only falling to around 80 degrees. Coastal areas will see daytime highs a few degrees cooler. In terms of humidity, you guessed it, days and nights will be sticky. Skies will be mostly sunny. Rain chances will be near zero. And that, my friends, is pretty much all there is to say about this week’s forecast.

Saturday, Sunday, and beyond

Is the high pressure system going to move away? Most of our best medium-range models indicate that there is a chance of change this weekend. Highs may drop a few degrees, and rain chances may rise to the 30 percent range (or higher). Next week also looks slightly cooler, but perhaps that’s only because the coming week looks so dang hot.

In brief: Today we discuss a bit about yesterday’s wider spread rain than expected in parts of the Houston area. A few additional storms are possible today before the heat parks itself back over Houston for much of next week.

Bertha recap

In terms of wind, Bertha was a nothingburger in Houston, as expected. In fact, I don’t believe any coastal location gusted much above 35 mph yesterday. In terms of rain, Bertha did overachieve in a chunk of the Houston area.

In Missouri City, several locations right along 90A picked up over 5 inches of rain which led to some rapid onset flash flooding. That extended back into Sugar Land as well. Meyerland saw about 3 inches of rain. Downtown Houston saw about 0.75″ of rain. In hindsight, while we mentioned that brief torrential rain was likely in spots yesterday afternoon, a Stage 1 flood alert probably would have worked best. It seemed as if the heaviest downpours would move fast enough to avoid that. Instead, everything congealed over Houston for a couple hours, and we got the above. While the tropical storm aspect of Bertha mostly did what was expected, the rain part remains a challenge.

Bertha’s remnants are passing southwest of San Antonio today, and they will continue through Mexico today and this weekend.

Today

A few showers or a thunderstorm are likely today across the area, with some onshore flow trailing Bertha. Atmospheric moisture levels are still pretty high, though decreasing. Still, that could mean again some locally heavy downpours this afternoon. Otherwise, look for highs in the mid-90s with sun and clouds.

Weekend

Saturday looks dry and hot with mid to upper 90s. Sunday should be similar, but there will be a slight tick up in available moisture for a few showers. So don’t be shocked to see that happen in a few spots.

Next week

Temperatures are going to surge once again next week back to near 100 degrees. Wednesday or Thursday should be the peak day, with highs around 101 to 103 in Houston. Rain chances will be shelved for the most part through Wednesday, but a backdoor front, sort of like what we saw on this past Wednesday evening could try to sneak through and provide a chance of storms either Thursday or Friday evening.

Slightly “less hot” weather is likely after Wednesday or Thursday, but we’ll watch trends through the weekend and update you on Monday.

In brief: Watch for areas of flash flooding over the next few hours as Bertha’s downpours press through the Houston region. Stage 1 or low-end 2 type flooding is expected in the impacted areas.

A flash flood warning is posted for portions of southwest Harris and Fort Bend County until 9 PM, as some bands of torrential downpours have pushed through the area. They are very slowly drifting north and west, but have dumped as much as 4 inches of rain over Missouri City in the last couple hours.

I would expect the flood advisory to eventually be expanded north and west as heavy downpours impact other parts of Harris and Fort Bend Counties, and another flash flood warning can’t be ruled out either. Watch for areas of street flooding over the next few hours, especially west of I-45. We should see storms and downpours peak over the next 2 to 3 hours and settle back down after 9 to 10 PM or so. Again, the core of the heaviest rain may slowly lift north and west, which should hopefully keep flooding from going beyond Stage 1 or perhaps low-end 2 in those areas.

Bertha itself has made landfall east of Houston and will continue off to the west or west southwest through the night and tomorrow.