Month: October 2024

In brief: Today’s post looks back at October, and explains why the weather has felt so incredibly hot in Houston this month. We also look ahead to the return of rain chances this week after a very long dry spell. And finally, we preview the arrival of substantially cooler weather during the latter half of next week.

Putting October’s record heat into context

You may have noticed that this October has felt hotter than normal, and you’re not wrong. A majority of days so far, 18, have reached a high temperature of 90 degrees or above. We have set daily highs on five days so far this month, including two extremely warm days (99 and 98 degrees) in the middle of the month before a front rolled through.

One way to assess the impact of heat is to look at three-day stretches. That is, if we take a three-day period in October, how does it rank among hottest three-day periods in October history? Well, in this case, four of the ten hottest three-day periods in October occurred during this month. The three days in the middle of the month produced absolutely unprecedented heat for this time of year.

So what caused this heat? One cannot escape the background signal of climate change when we’re setting daily high temperatures like this. But if we dig a little deeper there is more at play here. Let’s start with daily high temperatures: the average so far this month is 90.2 degrees, which is on pace to smash the previous record of 86.5 degrees set in 2016. So our days, at least during the 135 years of records we can refer to, have never been hotter. However, our average low temperature this month has been 62.5 degrees. This ranks 42nd all time. That is very far from abnormal. (Note these numbers are not final, but will not change too much before the end of the month.)

What we can derive from this data is that Houston, generally, has had a drier flow this month with a lot of easterly breezes. This has kept dewpoints down bit. Therefore we have had hot and sunny days, with cooler clear nights. Based on average temperature, this month will still end up among the five warmest Octobers of all time—the daytime highs have been that extreme—but comparatively speaking our nights have been relatively mild.

Monday

I write all of that to say the humidity is coming back this week, and you’re going to notice the southerly flow. Winds today will be from the southeast, with gusts up to 20 mph. We’ll see mostly sunny skies, with highs in the upper 80s. Low temperatures tonight will only fall into the lower 70s, so it will be very muggy outside.

Tuesday

Conditions will be similar to Monday, in terms of warmth and mostly sunny skies. The only difference is that our southeasterly winds will increase, and we may see some gusts up to 30 mph during the afternoon hours. So it’s really going to be blowing and going. Lows on Tuesday night may only fall into the mid-70s.

Wednesday

Expect partly to mostly sunny skies on Wednesday, with highs in the mid- to upper-80s. Some scattered rain chances return, especially for the coast, during the afternoon hours. Overall accumulations look fairly slight. Lows on Wednesday night will drop into the low 70s.

Halloween

It has not rained in 70 bajillion years in Houston, and of course the first day with really health rain chances comes on an outdoor holiday. Look, I’m not complaining about the rain, since we desperately need it. But on Halloween? Anyway, the good news is that while most of the region should see some light showers on Thursday, they’re likely to fading by around sunset, when trick-or-treating begins. The daytime showers will be driven by a very weak front that should help knock high temperatures into the lower 80s. Nighttime lows remain very warm.

Friday, Saturday, and Sunday

Highs over this period will range from about 80 to 85 degrees for the metro area, with a mix of sunshine and clouds. Each say will see a modest chance of rain, perhaps on the order of 30 to 40 percent. Nights remain warm and muggy. It’s worth noting that although the region will see some welcome rain chances this week, overall accumulations will likely be 1 inch or less for most locations. That is nice, but unlikely to bust our drought.

Next week

The first part of next week should see continued warm and muggy weather, with some modest rain chances. However, there is a very strong signal that by Wednesday or Thursday we’re going to see a fairly robust cold front that should knock our temperatures back to seasonal levels, with lows in the 50s or so. This is far enough out to retain a bit of skepticism, but it does seem pretty clear that we are going to see a significant pattern change some time next week.

In brief: Houston will see more of the same through Monday or so, with temperatures running around 7 to 10 degrees warmer than normal and lots of sunshine. We turn up the humidity after Tuesday with increasing rain chances, though the best rain chances may end up to our north. Halloween evening will be warm with at least some chance of rain.

40 years ago today was Houston’s (official) 4th wettest day on record, with hundreds of flooded homes and 10 inches of rainfall. The culprit was a stalled out cold front and several prior days of rain that had primed and saturated the ground. The current forecast has nothing remotely resembling rain until next week.

Today through Sunday

The next few days should feature more of the same in Houston. Expect plentiful sunshine, generally pleasant mornings in the 60s, and afternoon highs in the upper-80s, about 7 to 10 degrees warmer than normal and not far from records. Each morning could see pockets of dense fog in the area, so just be mindful of that. A reinforcing shot of drier air may help shave off a few more degrees on morning lows tomorrow or Sunday, but that should be the only evidence of it that we notice.

Monday & Tuesday

We begin to slowly transition here to a more humid type pattern. Look for daytime highs to stay in the mid to upper-80s, with nighttime lows in the 60s to low-70s. More sunshine is expected, but I would not entirely rule out an isolated shower on Tuesday.

Rest of next week & Halloween

The forecast becomes pretty straightforward in a generic sense after Tuesday. We will have clouds, sun, high humidity, and a chance of showers developing. Look for much warmer nights and mornings and slightly less hot afternoons. The highest chance of rain will probably be Wednesday or Thursday. Yes, there is a chance of rain on Halloween, but it remains much too early to get specific. We are confident that it will be a warm evening though.

I am a little concerned that the best rain chances will elude us to the north after Wednesday, but we still have time to watch this. Rain totals through Thursday are shown above, as forecast by the NWS. Expect some variability here with some places seeing minimal rain and others seeing perhaps an inch or two.

Next cold front?

There continues to be model evidence of a cool front after next weekend. Exactly how strong and when exactly it arrives remains to be seen. I’d still keep my expectations low, but the signal has remained at least!

Why the struggle to cool off?

Yesterday, Eric noted how the 6 to 10 day outlook showed warm temperatures leading into November. Now, as noted we are hopeful for a cool front somewhere around day 10 or so, but it will be unlikely to deliver actual *cold* air. In order to get true cold here in Texas, it usually either has to come straight outta Canada and down the Plains, your typical ‘norther. Or it has to be manufactured more locally, usually by clouds, rain, and chilly but not necessarily truly cold temperatures. That latter scenario happens to us sometimes in later November through March most often. This time of year, for hints of something beyond just an autumn tease or a setup for more frequent cool fronts, we would probably need to see cold air building up in western Canada.

If we look at the Euro ensemble forecast of jet stream winds on the maps above, you’ll notice what is basically a straight shot of green, yellow, orange, and red from China and Japan to southwest Canada. This is the core of the jet stream, and when it is doing this (extending across almost the entirety of the Pacific into Canada), it basically limits how cold it can get up there. It keeps weather active, it ushers in storms, but it never allows any cold to settle. Without that, we kind of have an elevated floor for how cold it can realistically get down here in Texas, as any cold coming out of Canada would be weak to begin with and continue to modify milder as it came southward. This can all change quickly, but there’s absolutely no sign of it right now in any real modeling. Until that gives, expect milder than normal weather to continue more often than not. We’ll still have periodic fronts, but they’ll mostly just reinforce comfortable humidity levels more than anything. Certainly not a bad thing, but it would still be abnormally mild.

In brief: Houston will continue to see very warm days, with highs generally in the upper 80s, for the rest of the month into early November. The only difference is that the modestly lower humidity we have seen this week will increase next week, and things are going to feel really humid for this late in the year. Rain chances remain possible later next week, but we’re unlikely to get the widespread drought relief we need.

Thursday

Calm winds and temperatures down near dewpoints in the lower 60s this morning are creating conditions to produce at least some patchy fog across parts of the area, but it will recede as temperatures warm up. We’re going toward the mid- to upper-80s for most locations today, with sunny skies and light easterly winds. Dewpoints will be low enough that the air feels at least somewhat dry outside. Low temperatures tonight will drop into the mid- to upper-60s for most locations, with the coast warmer as usual.

Friday

We’ll be a bit warmer on Friday, with much of the area in the upper-80s and a few locations potentially hitting 90 degrees. Sunny skies will prevail. The air will also feel a bit more humid, so this will be a pretty warm day overall. Lows on Friday night will only drop into the upper 60s.

Saturday and Sunday

Dewpoints drop back slightly for the weekend, so the air should again feel slightly drier. Days will still be quite warm, in the upper 80s for most locations. However, nights will be back into the mid-60s for most of Houston away from the coast. Skies will be almost uniformly sunny, so you should have no concerns about outdoor plans, except for atypical heat for late October.

Next week

We’ll see a continuation of warm, sunny days to start next week, with highs again in the upper 80s on Monday and Tuesday, and clear nights with lows in the upper 60s. However, the onshore flow should really start blowing and going at some point on Tuesday—we may see some fairly pronounced southerly winds—and this will act to boost humidity. We’re then likely to see partly cloudy and humid days during the second half of next week, with highs remaining in the upper 80s and nights in the low 70s. This is really incredibly warm for late October (including Halloween) into early November.

The only upside is that rain chances will finally return to the forecast by Wednesday or so. However, the overall likelihood of rain probably remains in the 30 percent range. In his post yesterday, Matt mentioned the possibility of a cold front by around next weekend, and there’s still a healthy chance of a front by Sunday (November 3) or Monday, but it’s something I would consider far from locked in.

In brief: More of the same is expected over the next few days in Houston, with cool-ish mornings and very warm afternoons, along with a good bit of sunshine. The weather pattern changes for a time next week toward humid with rain chances. Then, perhaps we can await our next front.

About 800 miles separate the two portions of Texas that have done well in the rain department this month: The mouth of the Rio Grande and the tippy top of the Panhandle. New Mexico has outperformed Texas, even with some serious flash flooding there recently.

But in general, we are far from alone right now in this dry pattern. The next couple weeks will bring us more of the same but also some potential for change, particularly next week. I think looking at the European ensemble for low temperatures the next two weeks shows how the pattern splits into 3 differing acts of weather.

Act I: The stable period through Sunday

Over the next several days, things will be pretty calm. We can expect daytime highs in the upper-80s, just a couple degrees shy of daily records. But if you want some autumn flavor, the mornings will remain fairly cool, in the 60s. These temperatures are still solidly at least 8 to 10 degrees warmer than usual. Rain chances will remain nil. We will get a weak reinforcing shot of drier air Friday that should extend this weather through at least Sunday and possibly Monday.

Act II: Revenge of humidity and rain chances

Next week sees a change. We’ll have both more unsettled weather and increasing rain chances, as well as much more humidity. Overnight lows will likely shift into the low-70s, about 10 to 15 degrees warmer than normal, while daytime highs will hold steady or even fall a few degrees due to clouds and rain chances.

I think we want to be realistic about rain chances next week. In a drought, sometimes you find ways to fail, and while I would still expect at least an inch or so of rainfall from scattered thunderstorms next week, the heavier rains, the 2 to 4 or 5 inch totals will probably be confined to a narrow corridor somewhere in the area along or northwest of highway 59. Something we will continue to watch. The European operational model shows this well below as a possible example of what could occur.

Regardless, we will see just a warm, humid, un-autumn-like week next week.

What this means for Halloween remains partially unclear. There will almost certainly be a chance of rain, but it will almost certainly also be warm. So plan for warm right now, but check back with us on the rain chances which may not become clear until early next week.

Act III: Additional autumn?

After next week’s pattern shift, we could see a return to something more typical for autumn. I would say there’s probably a 40 to 50 percent chance of a meaningful cold front around next weekend. The exact timing is uncertain, but there’s enough signal in the models for us to think there’s a decent chance. We’ll keep watching.