textproduct: New Orleans/Baton Rouge

KEY MESSAGES

Updated at 619 PM CDT Sat Jul 25 2026

- Impactful heat conditions will persist well into next week. Mid week will be the most intense days with heat indices 110-115 degrees.

SHORT TERM

(Now through Tuesday night) Issued at 1234 PM CDT Sat Jul 25 2026

A broad mid/upper-level ridge is currently draped across the Rockies, extending northward into Canada, southward into Mexico, and eastward into the Lower Mississippi Valley. The ridge will continue building toward the region through the weekend, with 500 mb heights rising into the middle and upper 590dm range. Warming through the 850-700 mb layer will strengthen subsidence and the mid-level cap, suppressing the usual summertime afternoon convective relief despite strong surface heating. This is supporting the development of a hot and remarkably dry late-July pattern across the region.

Visible satellite imagery shows a cirrus deck across northern portions of the CWA along with an isolated fair-weather cumulus field. The 12Z KLIX sounding measured a PW of 1.25", even lower than yesterday and between the late-July 10th percentile and observed minimum. Much of the additional drying compared to yesterday occurred above 500 mb. Although there's some boundary-layer moisture beneath the dry air aloft, strong subsidence, the strengthening cap, and a lack of meaningful forcing will make convective initiation very difficult. Light west to northwest low-level flow around a surface ridge centered along the northern Gulf Coast will become increasingly important through this weekend and into early next week. This land-based flow regime should allow temperatures to rise rapidly each day before the sea and lake breezes can penetrate very far inland. Highs will climb into the middle 90s this afternoon, with upper 90s becoming more prevalent Sunday as the upper ridge edges slightly closer to the CWA.

The main factor limiting the upper bound of heat indices today will be the extent to which drier air aloft mixes into the boundary layer. The decrease in dewpoints may not be dramatic, but even a small reduction can lower apparent temperatures by several degrees. By Sunday, the anomalously dry mid and upper-level air currently over the area will gradually shift away as flow around the eastern side of the central U.S. ridge carries somewhat higher moisture into the column from the northeast. Meanwhile, the surface ridge will drift southward into the Gulf, allowing low-level flow to become more westerly. This should maintain the existing shallow moist boundary layer and may deepen it slightly, but does not represent a classic deep southerly Gulf moisture return.

The current forecast still doesn't support enough of a large area of heat index values over 108 degrees Sunday to warrant a Heat Advisory at this time. The principal uncertainty remains afternoon dewpoints. Some guidance mixes dewpoints into the lower 70s over inland areas, which would keep heat indices somewhat lower. However, if dewpoints instead remain in the middle to upper 70s through peak heating, apparent temperatures could rise rapidly and produce more localized advisory-level values. Overnight lows will remain in the middle and upper 70s, with readings around 80 degrees across the New Orleans metro, near the tidal lakes, and along the immediate coast. Overnight recovery will consequently become increasingly limited as the heat event continues.

LONG TERM

(Wednesday through Friday night) Issued at 1234 PM CDT Sat Jul 25 2026

The broad upper-level ridge centered to the northwest will remain the dominant feature across the south-central United States during at least the first half of next week. Mid to upper 590dm heights, strong subsidence, and a warm 850-700 mb layer will extend across southeast Louisiana and southern Mississippi. The primary driver of the heat will therefore be the combination of deep-layer warming, abundant sunshine, suppressed convection, and a persistent west to northwest low-level flow that delays meaningful marine influence during the hottest part of the day.

Tuesday through Thursday (a slight delay from previous forecasts) appear to be the hottest portion of the forecast period. Inland highs will commonly reach the upper 90s, with some locations near 100 degrees. Did glance at record highs for early next week and forecast temps are right at to just below depending on location. Low-level moisture may become somewhat deeper early in the week even as the mid-level cap remains strong. This is the more concerning heat scenario, as dewpoints holding in the middle or upper 70s during peak heating would combine with temperatures in the upper 90s to produce heat indices of 108 to 115 degrees. Widespread Heat Advisory criteria appears increasingly likely Monday through at least Thursday. Portions of the I-10/12 corridors in LA and MS could approach or exceed the 113-degree Extreme Heat Warning threshold Tuesday and Wednesday. Similar values remain possible Thursday, but confidence decreases as the ridge begins to weaken.

The duration of the event will become increasingly important. Overnight lows will remain in the upper 70s across much of the area and near or above 80 degrees around New Orleans, the tidal lakes, and the immediate coast. Looking at previous similar events, locations around the tidal lakes sometimes get such little relief overnight. Have seen periods where KNEW's lowest heat index doesn't even drop below 100! The poor nighttime recovery across the CWA will allow heat stress to accumulate as this event progresses. We see this in the HeatRisk guidance which shows Extreme for about 25% of the CWA Monday, ~70% of the CWA Tuesday, and 80-90% Wednesday. This is consistent with the combination of hot afternoons, warm nights, and very limited convective relief. And speaking of convection, strong subsidence from upper ridging aloft should hold rain chances to near 10% Monday through Wednesday. A rogue storm could still briefly develop along a sea breeze, lake breeze, or remnant boundary late in the afternoon, but meaningful or widespread relief is not expected. Most locations will remain dry each day.

Changes should begin gradually around Wednesday as the ridge center starts shifting farther west and troughing deepens over the eastern United States. The Mississippi coastal counties and adjacent coastal waters will be closest to the weakening southeastern edge of the ridge and may see isolated/scattered afternoon convection return first. Rain chances around 20-30% are warranted there Wednesday, with substantially lower chances farther west beneath stronger subsidence. The eastern trough should exert a greater influence Thursday and Friday, lowering heights, weakening the cap, and allowing the sea breeze and other mesoscale boundaries to generate more typical afternoon convection. Rain chances increase into the 30 to 40 percent range. The increased clouds and convection should gradually lower daytime temperatures and heat indices, although Thursday could remain dangerously hot if the ridge breaks down more slowly than currently forecast. A faster erosion would provide earlier relief, while a slower transition would extend widespread heat hazards through Thursday and potentially into Friday.

AVIATION

(00Z TAFS) Issued at 623 PM CDT Sat Jul 25 2026

A shower/storm has developed over MSY this evening, so starting with a tempo for this locations. Elsewhere it remains dry and VFR conditions are anticipated through the period, again outside of the one cell over MSY. Expect winds to remain light and variable as well. (Frye)

MARINE

Issued at 1234 PM CDT Sat Jul 25 2026

Surface high pressure centered near the northern Gulf Coast will maintain relaxed conditions through today, with winds generally 5 to 10 knots and seas around 2 feet or less. The ridge will gradually settle southward Sunday and eventually become positioned near the Florida Keys by the middle of the week. This will establish a predominantly westerly flow regime across the local coastal waters. A typical summertime diurnal cycle will develop Sunday and carrying on through the forecast period. West to southwest winds will increase to around 10 to 15 knots during the evening and overnight hours, especially over the outer waters, then relaxing to 5 to 10 knots during the day. Seas will respond similarly, occasionally building to 2 to 4 feet offshore overnight and subsiding to around 1 to 2 feet during the afternoon. Strong subsidence will keep thunderstorms very limited through Tuesday. Storm coverage should begin increasing Wednesday near the Mississippi coastal waters and become more noticeable across the marine area Thursday and Friday as the upper ridge aloft weakens. Locally higher winds and seas will be possible near any late-week thunderstorms.

LIX WATCHES/WARNINGS/ADVISORIES

LA...None. GM...None. MS...None. GM...None.