In brief: In today’s post we provide an overview of Houston’s rain chances over the next four days, which will be elevated. Although there’s the potential for some heavy rain, we’re not too concerned about flooding at this time. A modest cool front arrives early next week.

Wet pattern overview

An upper-level low, in concert with the remains of Hurricane Polo, is bringing heavy rains to the Texas Hill Country this morning, and these storms are moving toward the I-35 corridor. This system will progress eastward across Texas, but it should stall later today to the west of Houston, near the Brazos Valley. Several inches of rain are possible from this system in Central Texas, but the Houston region should not see major effects aside from the potential for scattered showers and thunderstorms today.

For us, the best rain chances will come from Friday evening through Sunday morning as a weak frontal boundary slowly trudges through the area and stalls near the coast. With ample moisture this setup will bring the potential for heavy rainfall into the region during this time period, especially along the slow-moving boundary. Whether this rain falls just inland, or off the coast, will depend on precisely where the boundary stalls. All in all, through Sunday, most of the Houston region should pick up 1 to 4 inches of rain. We are not planning to issue a flood stage warning on our flood scale at this time, but we will continue to monitor things closely.

Quick space note

Weather permitting, four astronauts will launch to the International Space Station this morning aboard a Crew Dragon spacecraft from Florida. The crew includes NASA astronauts Jessica Watkins and Luke Delaney, Canadian astronaut Josh Kutryk, and Russian cosmonaut Sergey Teteryatnikov. Launch is set for 10:10am for this Crew-13 mission. We wanted to send a special shoutout to Kutryk, a fan of Space City Weather! Safe travels to all.

Thursday

The last day of September was another hot one, with high temperatures in the mid-90s for inland areas of Houston. Phew! Highs should peak in the lower 90s today across the city, and then after today or Friday, we should be able to say sayonara to the 90s for awhile. As noted above, the heavy rainfall due to Polo’s remnants should stay west of Harris and surrounding counties. However we will see scattered to widespread showers today, and the heaviest cells may quickly produce 1 or 2 inches of rain in isolated areas. Most locations will see considerably less, however. We’ll see some gusty southerly winds again later today. Overnight lows will drop into the upper 70s, and rain chances will slacken, but not go away entirely.

Friday, Saturday, and Sunday

It will be a soggy weekend, yes. But at the same time it’s not going to rain everywhere, all the time. There will definitely be breaks in the showers, so if you’re planning to attend a festival, or a college football game, or something else, do not abandon all hope. Nevertheless our region will see its best rain chances in weeks, and there will be more clouds than sunshine. Rain totals will vary widely, but most areas should get 1 to 4 inches. What concerns me most is the potential for these showers, tropical in nature, to produce briefly heavy rainfall. But again, aside from possibly the immediate coast, we don’t expect too much of that behavior over the Houston region. If our expectations change, of course, we’ll update here. Temperatures will gradually push downward, with highs in the upper 80s on Friday dropping to the mid-80s on Sunday, and overnight lows going from the upper 70s to lower 70s.

Next week

A slightly stronger cool front is really in the cards for early next week, likely arriving Monday night. This should lead us to sunny days in the 80s for most of next week, with nights in the 60s or lower 70s. Humidity will be lower, but as this is still one of our early fronts don’t expect miracles on that score. Still, it won’t be Houston-like houmidity, and after our long summer it’s going to feel fairly pleasant out there. Just don’t expect sweater weather just yet.

Tropics

You may start to see some noise about tropical development in the Southern Gulf or Bay of Campeche next week, and some of our models are showing the potential for modest development there. We don’t have any real concerns about this in Texas, however, as any systems that develop there next week will most likely move to the northeast, away from the state.

In brief: After today, which will be windy, Houston will face a distinctly wetter pattern from Thursday through the weekend. We don’t have any specific flooding concerns, but will be watching the situation closely. Next week looks cooler.

A word about wind

It’s been a minute since we’ve seen gusty conditions in Houston, but that will change later today, particularly during the afternoon and early evening hours. (We’ll also see some gusty conditions on Thursday afternoon, but likely less so than today). This will be due to a rather tight pressure gradient, with our area of Texas lying between low pressure over West Texas and the Panhandle, and high pressure over the Eastern United States. This will effectively create strong south to north winds across our region (and pretty much up the entirety of I-45 to Dallas later today. Expect gusts this afternoon of 25 to 30 mph, which are nothing incredible, but will be notably higher than we’ve experienced for much of August and September.

Wednesday

Aside from breezy conditions, skies today will be partly sunny with high temperatures generally in the lower 90s. Overall rain chances will probably be 30 or 40 percent, with coverage slightly higher than on Tuesday. As we saw yesterday, with very high levels of atmospheric moisture where showers do set up they can drop briefly heavy rain. Lows tonight will fall into the upper 70s for most locations.

Thursday, Friday, Saturday, and Sunday

During this four day period we will see several factors at play, including a slow-moving cool front, a rich surge of atmospheric moisture, and plenty of lift that will support shower activity. There won’t be wall-to-wall showers, but there will likely be bursts of activity each day, beginning Thursday afternoon. On Thursday and Friday showers and thunderstorms should be more likely to the west and north of Houston, with the focus of shower activity shifting closer to the coast this weekend. Overall most locations should pick up 2 to 4 inches of rainfall through Sunday, but in these kinds of setups we can definitely see higher accumulations. We will be monitoring the potential for flooding, but as of yet do not see anything we want to specifically call out.

In terms of temperatures, we should see partly sunny skies and highs of around 90 degrees on Thursday, with more clouds through the weekend and highs falling into the mid-80s. Overnight lows will drop from the upper 70s on Thursday night to around 70 degrees by the weekend.

Next week

Rain chances should start to recede by Monday or so, after which a weak front may move into the area. A slightly stronger cool front may move in later next week, but I’m not certain of that, or the details. Suffice it to say we should be in the 80s rather than the 90s next week, which will be a nice change, with the potential for some cooler nights.

In brief: Houston faces a couple of more days of late summer weather before a significant pattern change brings us a soggy weekend. After that we expect cooler conditions next week. Is it goodbye 90s?

Tuesday

Today will bring partly sunny skies into the region, with high temperatures in the low- to mid-90s as late September heat stubbornly holds on for a few more days. Winds will be from the southwest, gusting up to 15 or 20 mph during the afternoon hours. Areas near Matagorda Bay may see a few showers, but overall chances closer to Houston, and within the metro area, look to be low today—probably in the 10 to 20 percent range. Lows tonight will only drop into the upper 70s, and briefly.

As for the Astros and their playoffs against the Chicago White Sox, with games here locally on Tuesday, Wednesday, and Thursday, I would not expect the roof to be open at all for the AL Wild Card Series.

Wednesday

This day will be similar to Tuesday, although rain chances will be slightly higher, perhaps in the 20 to 30 percent range. Expect another muggy night.

Thursday

Skies should transition to become mostly cloudy on Thursday, with highs likely in the vicinity of 90 degrees. Rain chances will be improving, but as we discussed yesterday, the bulk of the rains during the mid-week period will be concentrated over central Texas, due to moisture from the remnants of Hurricane Polo. I’d say the region has about a 50 percent chance of rain on Thursday, but the likelihood of heavier rainfall will not pick up until Friday, or the weekend.

Friday, Saturday, and Sunday

This is when atmospheric moisture peaks, and each of these days will see a healthy rain chance in the 60 to 80 percent range. Overall accumulations this weekend will likely be in the vicinity of 1 to 4 inches across the metro area, but some areas may see higher isolated totals. For now we are not going to issue a flood scale warning, but Matt and I are watching things closely to see how things evolve. Mostly, we think this just will be a soggy weekend, with on-and-off showers putting a damper on some outdoor activities. Due to rains and cloud cover, expect highs in the mid- to upper-80s this weekend, with overnight lows in the 70s.

Next week

Highs next week should remain in the 80s, and our nighttime temperatures will depend on the extent to which a series of fronts make it into the region. Right now I think it’s possible that a weak front makes it in on Monday or Tuesday, with the possibility of a another front later in the week. The details on all of this are very much fuzzy at this point, however.

In brief: In today’s post we take a broader look at rains expected to move into Texas from the remains of a Pacific hurricane, and look ahead to cooler and wetter weather across the Houston region toward the end of this week.

Polo’s remains bring Texas rains

Hurricane Polo, a powerful storm in the Pacific Ocean, is about to make landfall over Baja Peninsula and then will move toward Texas over the next couple of days. There it will bring the potential for heavy rainfall. Houston, under less of a threat, will see rains later this week, which we’ll discuss below. But to start I wanted to highlight the threat from Polo to central Texas. The following is a snippet from our companion site, The Eyewall.

Copious amounts of moisture will surge into the Desert Southwest and eventually the Southern Plains and Texas from Hurricane Polo. The moisture from Polo and a slow or stalling cold front will probably focus repeating rounds of rain from Hill Country into North Texas. Those areas are already under a moderate risk (level 3/4) for flash flooding on Wednesday, and that will likely extend into Thursday as well.

Rain totals are likely to end up in the 4 to 8 inch range from south of San Antonio through Dallas and perhaps up toward Durant, OK through Friday. There is a chance that some areas see as much as 10 to 12 inches though, as we know Texas flood history is littered with these types of remnant Pacific hurricane events.

For now the more serious flooding concerns are likely to stay north and west of the Houston region. Texas folks in Hill Country and the Metroplex should monitor the next couple days of forecasts very closely and be prepared for disruptions on Wednesday and Thursday.

Monday, Tuesday, and Wednesday

Locally, we don’t expect too much rainfall over the next few days. Rain chances through Wednesday will be on the lower end, probably 20 to 30 percent each day. Yes, there could be a few more clouds, and we certainly cannot rule out some thunderstorms, but any moisture related to Polo should remain well to our west. Highs each day will be in the low- to mid-90s with plenty of humidity. Nights will be muggy, in the upper 70s for the most part.

Thursday, Friday, Saturday, and Sunday

This is the period when we expect improved rain chances across the Houston region as available moisture in the atmosphere surges upward. Unfortunately, I cannot give you a precisely detailed forecast for each day. However, rain chances should be 50 percent or above, with with partly to mostly cloudy skies. At this point Friday appears likely to have the best overall chance for rain, but this could shift over the next couple of days. In terms of overall accumulations, they will vary widely, but I expect most of the Houston region to pick up 1 to 4 inches of rainfall through Sunday. Again we’ll need to fine tune this forecast as we get closer.

In terms of daily temperatures, the cloud cover, rain, and a weak front should help pull highs down into the 80s on most days, with overnight lows in the mid-70s. So basically we’ll be at pretty seasonable levels for early October.

Next week

The rains should subside by Monday or Tuesday of next week, after which point something of a stronger front may arrive to possibly push nights into the 60s during the second half of the week. More on that in the coming days as we get more clarity on the situation.