Houston Weather Forecast: Heat, Rain Chances & What to Expect This Week

Houston has just finished seven consecutive days at 100F or above. Every one of them ran six to eight degrees above normal, and the last three all hit exactly 100F.

That streak ends today. The National Weather Service has the next seven days at 92 to 95F — which is to say, normal. The hottest day of the week ahead is five degrees cooler than the coolest day of the week behind.

But the number that matters for standing outside is going the other way.

What is the Houston forecast this week?

Highs in the low-to-mid 90s every day, nights in the high 70s, and a daily chance of afternoon storms that mostly will not reach you. Here is the whole seven days as the NWS has it:

“Chance” is the probability of at least 0.01 inch at any one point; “Rain” is the total actually forecast for the day. They are not the same thing, and this week they point in different directions — see below.

Overnight lows sit at 78 to 80F all week. Sunday is the outlier in both directions: the only day forecast as plainly Sunny, the lowest rain chance of the week at 6%, and the lowest feels-like at 99F.

Is this a heat wave in Houston?

No — and more usefully, the one that just happened is over. The week Houston has just come through was the heat event. The week ahead is ordinary late-August weather.

The climate report for Bush Intercontinental makes the contrast plain. These are the observed highs against the 1991–2020 normal for each date:

Seven days, seven departures of +6 or more, and not one of them a record — the record for 27 August is 109F, set in 2011. It was persistently, unusually hot without ever being historically hot, which is the shape most Gulf Coast heat takes.

It was hot overnight too, and that is the part that does the damage. On 27 August the low was 82F against a normal of 75F, and the day’s average of 91F ran seven degrees above normal. A night that does not drop below 82F gives a house without air conditioning no chance to shed the day’s heat.

Why does it feel hotter as the temperature falls?

Because the humidity comes back. The air temperature drops about three degrees over the week while the heat index climbs five, and those two facts have the same cause.

A frontal boundary has been sitting almost stationary along the I-10 corridor. It clears offshore this morning, and behind it the wind turns north-to-easterly and drags in a slightly drier air mass — which is why today and tomorrow feel less oppressive than the raw temperature suggests, at 101F and 100F against highs of 95F.

Then the flow turns back onshore, the Gulf moisture returns, and the gap between the thermometer and your skin widens from six degrees on Saturday to fourteen degrees by Wednesday. By then a 93F afternoon feels like 106F.

Practically: the middle of next week is the part to plan around, not today. Wednesday is the coolest-looking day on the forecast and the most dangerous one to spend outside.

What do the rain chances actually mean?

Much less than they look like. A “35% chance of rain” is the probability that any one spot gets at least one hundredth of an inch — it says nothing about how much, how long, or how much of the city.

Put the two side by side and the week’s chances add up to 0.19 inches of forecast rain in total. The relationship between the two columns is not just weak, it is close to inverted:

• The wettest day of the week is Friday at 0.06" — and Friday has the second-lowest chance on the board, 17%.
• The highest chance of the week is Tuesday at 35% — and Tuesday brings 0.03".
• Sunday’s 6% is the only honest-looking number, because it corresponds to 0.00".

This is not the forecast being wrong. It is what a sea-breeze summer looks like: convection fires along the boundary in the afternoon, dumps hard on a few square miles for twenty minutes, and misses everywhere else. A high percentage means somebody gets wet. It has never meant you will.

If you are watering a lawn or planning around drought, read the inches column and ignore the percentages. If you are deciding whether to carry an umbrella to an outdoor evening, read the percentages.

Are there any weather warnings in Houston right now?

No heat products of any kind, anywhere in Texas. Not a Heat Advisory, not an Excessive Heat Warning, not a watch — despite a week of 100F days and a forecast heat index touching 106F.

The whole state has two active alerts as of this morning:

The flood advisory was issued at 5:39 a.m. and runs for barely an hour — it is the tail of the overnight storms along the departing boundary, not a signal about the week.

Two active alerts for a state of thirty million people in late August is a quiet board. It is worth stating plainly because the absence of a heat advisory during a 100F streak surprises people: the advisory thresholds on the Gulf Coast are set against what the local population is acclimatised to, and a Houston August that runs six degrees above normal still does not clear them.

What is driving the pattern?

A ridge and a sea breeze, in that order. The NWS Houston/Galveston forecasters describe a mid-to-upper-level ridge centred over West Texas that expands eastward through early next week, with disturbances arriving from the Gulf underneath it.

That combination is what produces the shape of this forecast:

• The ridge caps the heat near normal rather than driving it higher. The forecasters’ own summary for today is that it will be hot “but at least not in the triple digits”.
• The disturbances plus the afternoon sea breeze keep a daily storm chance alive without ever organising into a soaking. Hence 30-something percent chances attached to hundredths of an inch.
• The severe threat is low. What is possible with the stronger storms is gusty winds, brief heavy downpours and frequent lightning — the ordinary hazards, not the organised ones.

The atmosphere is very wet: precipitable water over the region has been running 2.0 to 2.3 inches, which is near the top of the range for the date and is why the storms that do fire can drop a lot of water very quickly on a small area.

When does the weather actually change?

Not within this forecast. Every one of the next seven days is a variation on hot, humid, and briefly stormy in the afternoon — the NWS key message is explicitly that “hot and humid conditions with low chances for showers/storms will continue into next week”.

The two things worth watching past this window:

• Whether the heat index keeps climbing past Wednesday. It has risen every day from Sunday onward in this run. If onshore flow persists and the ridge holds, that is the variable that reaches an advisory threshold first — not the air temperature.
• The Gulf. Late August into September is the climatological peak of the Atlantic season, and the disturbances feeding this pattern are coming off the same water. Nothing in this forecast implies a tropical system, and none is indicated; it is simply the season in which the sea-breeze pattern and a tropical wave can stop being separate things.

For anything beyond seven days, the honest answer is that a daily forecast does not know. Seasonal guidance is a different product with different skill, and we keep the US-wide version of it on a separate page .

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