September Weather in Lahaina Hawaii, United States

Daily high temperatures are around 87°F, rarely falling below 85°F or exceeding 90°F.

Daily low temperatures are around 72°F, rarely falling below 68°F or exceeding 76°F.

For reference, on August 26, the hottest day of the year, temperatures in Lahaina typically range from 73°F to 87°F, while on January 28, the coldest day of the year, they range from 65°F to 81°F.

The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on September. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Villalba, Puerto Rico (5,796 miles away) is the far-away foreign place with temperatures most similar to Lahaina (view comparison).

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The month of September in Lahaina experiences increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 27% to 36%.

The clearest day of the month is September 1, with clear, mostly clear, or partly cloudy conditions 73% of the time.

For reference, on October 30, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 42%, while on January 18, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 78%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Lahaina, the chance of a wet day over the course of September is essentially constant, remaining around 14% throughout.

For reference, the year's highest daily chance of a wet day is 23% on January 11, and its lowest chance is 9% on June 19.

Rainfall

To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during September in Lahaina is essentially constant, remaining about 1.0 inches throughout, and rarely exceeding 3.0 inches or falling below -0.0 inches.

Over the course of September in Lahaina, the length of the day is decreasing. From the start to the end of the month, the length of the day decreases by 34 minutes, implying an average daily decrease of 1 minute, 11 seconds, and weekly decrease of 8 minutes, 14 seconds.

The shortest day of the month is September 30, with 11 hours, 57 minutes of daylight and the longest day is September 1, with 12 hours, 31 minutes of daylight.

The earliest sunrise of the month in Lahaina is 6:10 AM on September 1 and the latest sunrise is 7 minutes later at 6:17 AM on September 30.

The latest sunset is 6:41 PM on September 1 and the earliest sunset is 27 minutes earlier at 6:14 PM on September 30.

Daylight saving time is not observed in Lahaina during 2024.

For reference, on June 20, the longest day of the year, the Sun rises at 5:46 AM and sets 13 hours, 24 minutes later, at 7:10 PM, while on December 21, the shortest day of the year, it rises at 6:59 AM and sets 10 hours, 52 minutes later, at 5:51 PM.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

The figure below presents a compact representation of key lunar data for September 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The chance that a given day will be muggy in Lahaina is gradually decreasing during September, falling from 83% to 80% over the course of the month.

For reference, on August 16, the muggiest day of the year, there are muggy conditions 85% of the time, while on March 5, the least muggy day of the year, there are muggy conditions 27% of the time.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Lahaina is gradually decreasing during September, decreasing from 13.8 miles per hour to 12.8 miles per hour over the course of the month.

For reference, on July 2, the windiest day of the year, the daily average wind speed is 15.5 miles per hour, while on January 10, the calmest day of the year, the daily average wind speed is 11.4 miles per hour.

The hourly average wind direction in Lahaina throughout September is predominantly from the east, with a peak proportion of 96% on September 1.

Lahaina is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average surface water temperature in Lahaina is essentially constant during September, remaining around 80°F throughout.

The highest average surface water temperature during September is 80°F on September 20.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

Temperatures in Lahaina are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

The average accumulated growing degree days in Lahaina are rapidly increasing during September, increasing by 842°F, from 6,214°F to 7,056°F, over the course of the month.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy in Lahaina is gradually decreasing during September, falling by 0.8 kWh, from 7.0 kWh to 6.2 kWh, over the course of the month.

For the purposes of this report, the geographical coordinates of Lahaina are 20.874 deg latitude, -156.677 deg longitude, and 36 ft elevation.

The topography within 2 miles of Lahaina contains very significant variations in elevation, with a maximum elevation change of 1,076 feet and an average elevation above sea level of 141 feet. Within 10 miles contains very significant variations in elevation (5,771 feet). Within 50 miles also contains extreme variations in elevation (10,069 feet).

The area within 2 miles of Lahaina is covered by water (45%), shrubs (22%), artificial surfaces (15%), and grassland (12%), within 10 miles by water (61%) and trees (18%), and within 50 miles by water (85%).