Slidell (LA) Temperature by Month

The average annual maximum temperature in Slidell, Louisiana, United States of America is 25°C (77°F), with daytime highs ranging from 16°C (61°F) in January to 33°C (91°F) in August. This page covers monthly averages, day-night differences, and how Slidell compares to cities worldwide.

With significant temperature fluctuations, Slidell enjoys distinct seasons year-round. Nighttime lows range from 23°C (73°F) in August to 5°C (41°F) in January.

The chart below illustrates the average maximum day and minimum night temperatures in Slidell by month:

The minimum temperature is often recorded between 4 AM and 6 AM, while the highest temperature is usually reached at 3 PM, when the sun's heating effect is strongest. August, the warmest month, gets 251 hours of sunshine.

The chart below shows the average temperature throughout the year:

Slidell's average annual maximum temperature is 25°C (77°F). To put that in context, here's how it compares to a few well-known destinations:

Rome, Italy averages 20°C (68°F) annually, with reliably warm summers and comfortable winters.

Queenstown, New Zealand averages 10°C (50°F) annually, remember seasons are flipped, so its coldest months fall in June and July.

San Francisco, USA averages 19°C (66°F) annually, but with little seasonal variation, summers are often cool and foggy, winters mild.

Adelaide, Australia averages 21°C (70°F) a year, with warm summers, mild winters, and relatively low rainfall year-round.

Temperature alone doesn't tell the whole story, humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.

In Slidell, January is the coolest month, with average highs of 16°C (61°F) and humidity around 75%, considered high. In August, the warmest month, temperatures average 33°C (91°F) with 79% humidity, conditions that feel high. For a full picture, see our humidity page.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

Whether a city sits on the coast or deep inland makes a significant difference to its climate. Coastal areas tend to have more stable temperatures year-round, large bodies of water absorb heat slowly in summer and release it gradually in winter, keeping extremes in check. Cities far from the sea don't benefit from that buffer, which is why continental climates tend to have hotter summers and colder winters than their coastal counterparts at the same latitude.

For more on Slidell's weather, including monthly rainfall, sunshine hours, and humidity, visit our Slidell climate page.