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September Weather in Alto, United States

Last updated: June 24, 2025

In Alto, United States, the average temperature in September reaches a warm 26°C (80°F). Be prepared for a range of temperatures, as the minimum can drop to 11°C (52°F) while the maximum can soar to 39°C (103°F). With an average humidity of 69%, you may feel the heat even more. Additionally, expect about 97 mm (3.8 in) of precipitation over 11 days, so it’s wise to keep an umbrella handy!

September Temperature in Alto

In September in Alto, the average temperature is 26°C (80°F). Maximums can reach 39°C (103°F), while minimums can drop as low as 11°C (52°F). Be prepared for warm days and cooler nights when traveling during this month.

September Weather in Alto: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Alto, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Alto, September typically has an average temperature of 26°C (80°F), with highs reaching up to 39°C (103°F) and lows dropping to around 11°C (52°F).
JanFebMarAprMayJunJulAugSepOctNovDec505262667581848479695854
Data source: Temperature data for Alto generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Alto

In Alto in September, the total precipitation amount is 97 mm (3.8 in) over the course of 11 days.

September Precipitation Trends in Alto

The chart displays monthly precipitation patterns in Alto, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Alto, September typically receives around 97 mm (3.8 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec101135115142145111801029712276116
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Alto

In Alto in September, humidity is 69%. With an average temperature of 26°C (80°F), this humidity feels like a warm, steamy embrace, making outdoor activities slightly sweaty and requiring frequent breaks for hydration but still inviting for leisurely strolls or exploring local attractions.

September Average Humidity in Alto

This chart illustrates the average monthly humidity levels in Alto, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Alto is approximately 69%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec80%80%78%79%81%77%71%67%69%73%82%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Alto

In Alto in September, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Alto.

Maximum UV Index Levels in Alto for September

The chart shows the monthly maximum UV Index (UVI) for Alto in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Alto typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec478111111121110864
Data source: Alto September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Alto Compares to Other Months

Weather in Alto varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Alto, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Alto, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather10°C (50°F)101 mm (4.0 inches)79%moderate
February Weather11°C (53°F)135 mm (5.3 inches)80%high
March Weather16°C (62°F)115 mm (4.5 inches)78%very high
April Weather19°C (66°F)142 mm (5.6 inches)79%extreme
May Weather24°C (75°F)145 mm (5.7 inches)81%extreme
June Weather27°C (81°F)111 mm (4.4 inches)77%extreme
July Weather29°C (84°F)80 mm (3.2 inches)71%extreme
August Weather29°C (85°F)102 mm (4.0 inches)67%extreme
September Weather26°C (80°F)97 mm (3.8 inches)69%very high
October Weather21°C (70°F)121 mm (4.8 inches)73%very high
November Weather14°C (58°F)76 mm (3.0 inches)82%high
December Weather12°C (54°F)116 mm (4.6 inches)87%moderate

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