Atlanta, Georgia Weather in September: What to Expect and How to Prepare

September in Atlanta, Georgia is a true transition month. The peak summer heat begins to ease, but it can still feel hot and muggy—especially early in the month. If you live in Atlanta, are planning a visit, or are scheduling an outdoor event, understanding Atlanta’s September weather helps you pack, dress, and plan with fewer surprises.

Quick Snapshot: Atlanta Weather in September

Here’s a simple overview of what September usually feels like in Atlanta:

Conditions can vary from year to year, but this table reflects what Atlanta residents commonly experience in September.

Temperature: From Summer-Like to Mild

Daytime temperatures

During the day, Atlanta in early September often still feels like summer:

• Highs commonly reach the low to upper 80s°F
• A few hotter days in the upper 80s to around 90°F are still possible
• Heat plus humidity can make it feel a bit warmer than the actual temperature

By late September, many days feel more moderate:

• Highs are more likely in the upper 70s to low 80s°F
• Midday sun can still be strong, especially on clear days

Nighttime and early morning

Mornings and nights are usually comfortable:

• Lows often settle in the low to upper 60s°F
• Some nights—especially later in the month—can dip into the upper 50s°F in parts of the metro area

If you’re commuting early or staying out late on a patio in Midtown, the temperature swing between afternoon and night can be noticeable. A light layer is useful by the back half of the month.

Humidity, Rain, and Thunderstorms

Humidity levels

Atlanta’s September humidity is still noticeable, but often less oppressive than July and August:

• Expect sticky days early in the month, especially after rain
• As the month goes on, some days feel more pleasant and less muggy
• Air conditioning is still commonly used, particularly in the afternoons

Rain patterns

September is not Atlanta’s rainiest month, but showers and storms are still part of the picture:

• Pop-up afternoon thunderstorms can develop on warm, humid days
• Some days are completely dry; others bring brief but intense downpours
• Rain can be highly localized—it might pour in Buckhead while staying dry in Decatur

Plan flexible outdoor activities and have a backup indoor option when you can.

Tropical influences and storm risk

September falls in the heart of the Atlantic hurricane season. Atlanta is inland, but remnants of tropical storms or hurricanes that make landfall in the Southeast can still affect the city:

• Increased cloud cover and rain over a day or two
• Periods of gusty wind
• Isolated flooding in low-lying or poorly drained areas

For updated local information, Atlanta residents often rely on:

• National Weather Service – Peachtree City Office
  4 Falcon Drive, Peachtree City, GA 30269
  Phone: (770) 486-1133

This office issues local forecasts, watches, and warnings for metro Atlanta.

Air Quality and Allergies

Air quality considerations

By September, extreme summer smog days are usually less frequent than in peak summer, but air quality can still vary:

• Warm, stagnant days can bring moderate air quality concerns
• Rainy, breezy days often help clear the air

Residents who are sensitive to pollution or have respiratory concerns often keep an eye on daily Air Quality Index updates from local news or regional environmental agencies.

Allergies: Late summer into fall

Atlanta’s allergy seasons overlap, and September can be active for some people:

• Ragweed and other fall pollens are often in the air
• Mold spores can increase after rainy or humid periods

Anyone sensitive to these triggers may want to keep common strategies ready, especially when planning long outdoor activities on the BeltLine or at Piedmont Park.

What to Wear in Atlanta in September

Packing or planning your wardrobe for September in Atlanta is mostly about layering and versatility.

Everyday clothing

For most days:

• Short-sleeve shirts or light tops
• Lightweight pants, skirts, or shorts
• Breathable fabrics (cotton, linen, moisture-wicking materials)

For evenings or air-conditioned indoor spaces:

• A light cardigan, denim jacket, or thin pullover
• Closed-toe shoes or sneakers if you’ll be walking a lot around Downtown, Midtown, or West Midtown

Footwear

If you’ll be exploring:

• Comfortable walking shoes for sidewalks, MARTA commutes, and parks
• Sandals are fine for many days, but closed shoes are better after heavy rain or in muddier spots (like some areas of larger parks or trails).

Rain planning 🌧️

Because showers can pop up:

• Keep a compact umbrella or light rain jacket in a bag or car
• Consider water-resistant shoes or something that dries quickly if you’ll be out all day

Outdoor Activities: Making the Most of September Weather

September weather is often great for getting outside in Atlanta, especially later in the month when the heat eases.

Popular outdoor spots that pair well with September weather include:

• Piedmont Park – Good for walking, jogging, and festivals; expect warm afternoons but pleasant evenings.
• Atlanta BeltLine Eastside Trail – Lively in September; plan for sun protection in exposed areas.
• Stone Mountain Park (east of Atlanta) – Hiking is more comfortable earlier in the morning or closer to sunset.
• Atlanta Botanical Garden – Late summer blooms, with shade in certain garden areas.

Planning tips:

• Midday (roughly 1–4 p.m.) can still feel hot and sticky, especially early in the month.
• Morning or early evening activities are usually more comfortable.
• If you’re attending outdoor events or festivals, consider hat, sunglasses, sunscreen, and water.

Travel and Daily Life: How September Weather Affects Plans

Commuting and traffic

Rainy September afternoons can:

• Slow traffic on major roads like I-75/85, I-285, and GA 400
• Reduce visibility during heavy downpours
• Create slick roads, particularly after a dry spell when oil buildup mixes with rain

Building a bit of extra time into commutes on stormy days is common for Atlanta residents.

Events, sports, and festivals

September is a busy event month in and around Atlanta, with:

• Sporting events at Mercedes-Benz Stadium and Truist Park
• Various festivals in Piedmont Park, Grant Park, and other neighborhoods

Weather-wise:

• Early September events can still have a summer feel—hot sun and humidity
• Later in the month is often more comfortable, but bring a light layer for evening events
• Keep an eye on forecasts for lightning or heavy rain delays at outdoor venues

Daylight, Sunrise, and Sunset

As Atlanta moves into fall, daylight hours gradually decrease:

• Early September: Longer daylight, with sunsets still in the evening hours suitable for outdoor dinners or walks
• Late September: Noticeably earlier sunsets, making evenings cooler and darker sooner

This shift affects:

• After-work activities – Less time for long outdoor outings in full daylight
• Children’s activities – Evening practices may finish in twilight or under lights by month’s end

Safety and Preparedness Tips for September Weather

Even though September is not winter-storm season, it’s still worth keeping some basic weather awareness in mind.

During storms or heavy rain

• Monitor local radio, TV, or weather apps for severe thunderstorm or flash flood alerts
• Avoid driving through standing water on roads, especially underpasses or low areas
• Secure outdoor items at home (patio furniture, trash bins) if strong winds are predicted

For official local weather alerts and forecasts, residents can refer to:

• National Weather Service – Peachtree City Office
  4 Falcon Drive, Peachtree City, GA 30269
  Phone: (770) 486-1133

Heat and sun

On hotter September days:

• Use sunscreen, especially around midday
• Seek shade or air conditioning during the hottest part of the day
• Carry water if walking around Downtown, the BeltLine, or large outdoor venues

How September Compares to Other Months in Atlanta

For planning moves, trips, or events, it helps to see where September fits in Atlanta’s annual weather pattern:

• Compared to August: Slightly cooler and sometimes less humid, but still summer-like.
• Compared to October:Warmer and more humid; October usually feels distinctly more “fall-like.”
• Compared to winter months: September is much warmer, with no typical cold snaps or freezes.

If you like warm, but not extreme, weather, September is often a favorable time to be in Atlanta—especially in the second half of the month.

Practical Checklist: Visiting or Living in Atlanta in September

Use this quick list to stay comfortable and prepared:

• Clothing:
  • Light, breathable outfits for warm days
  • A light jacket or sweater for some evenings
• Weather gear:
  • Compact umbrella or rain jacket
  • Comfortable walking shoes or sneakers
• Sun and heat:
  • Sunscreen, sunglasses, hat
  • Refillable water bottle, especially if walking or using MARTA plus walking
• Planning:
  • Check the day’s forecast before outdoor activities or events
  • Allow extra drive time if storms are expected
  • Watch for tropical system remnants that may bring periods of heavier rain

With this understanding of Atlanta’s September weather—warm days, somewhat cooler nights, lingering humidity, and occasional storms—you can plan your day-to-day life, trips, and outdoor activities around the city with more confidence and fewer surprises.