August weather forecast
Illinois, USA

August in Illinois, while still deep within the summer's grip, hints at a forthcoming transition as the days gradually start to shorten. The northern regions, in proximity to Wisconsin, typically experience daytime temperatures in the upper 70s°F to low 80s°F. The southern parts, adjacent to Kentucky, although warmer, witness a slight decline from July's highs, ranging in the mid to upper 80s°F.

Chicago remains a hub of summer activities, with beachgoers, tourists, and residents alike seeking to maximize the season's tail end. Lake Michigan's influence, always present, continues to moderate extreme temperatures, especially near its shores. Rainfall, though sporadic, can occasionally be heavy, accompanied by thunderstorms energized by the humid atmosphere.

Nights in August, while still warm, edge towards the cooler side, especially as the month progresses. Temperatures generally oscillate between the low to mid-60s°F. These slightly cooler nights hint at the impending arrival of fall.

When set against July, August demonstrates a subtle decline in both temperatures and humidity levels. While heatwaves are still plausible, they become less frequent. The month's end marks the waning phase of summer, setting the stage for the temperate and colorful embrace of September's fall.

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• Chicago - August »
  With an average ocean temperature of 73.9°F (23.3°C), August is the month with the warmest seawater in Chicago. With an average ocean temperature of 73.9°F (23.3°C), August is the month with the warmest seawater in Chicago.
• Aurora - August »
  August sees a slight decline in Aurora's temperature, providing some relief to the residents from July's intense heat. On the last day of August, in Aurora, sunrise is at 6:18 am and sunset at 7:29 pm CDT.
• Rockford - August »
  August carries on the warm summer trend in Rockford, with just slight drops in the average high and low temperatures compared to July, standing at 78.1°F (25.6°C) and 60.6°F (15.9°C) respectively. In Rockford, in August, it is raining for 14.8 days, with typically 2.32" (59mm) of accumulated precipitation.
• Joliet - August »
  On the first day of August in Joliet sunrise is at 5:47 am and sunset at 8:10 pm. In Joliet in August, it is raining for 15.8 days, with typically 2.83" (72mm) of accumulated precipitation.
• Naperville - August »
  The advent of August in Naperville brings an average high-temperature of a still warm 80.1°F (26.7°C), exhibiting minor difference from the previous month. In Naperville, in August, during 15.3 rainfall days, 1.81" (46mm) of precipitation is typically accumulated.
• Springfield - August »
  In Springfield, during August, the rain falls for 14.8 days and regularly aggregates up to 2.28" (58mm) of precipitation. On the first day of August in Springfield, sunrise is at 5:57 am and sunset at 8:12 pm.
• Peoria - August »
  On the last day of August, in Peoria, sunrise is at 6:24 am and sunset at 7:32 pm CDT. In Peoria, during August, the rain falls for 12.3 days and regularly aggregates up to 1.3" (33mm) of precipitation.
• Elgin - August »
  In Elgin during August, the rain falls for 17 days and regularly aggregates up to 2.68" (68mm) of precipitation. The months with the highest UV index in Elgin are July and August, with an average maximum UV index of 6.
• Waukegan - August »
  July and August, with an average maximum UV index of 6, are months with the highest UV index in Waukegan, Illinois. The months with the most sunshine in Waukegan are July and August, with an average of 10.5h of sunshine.
• Champaign - August »
  June through August, with an average maximum UV index of 6, are months with the highest UV index in Champaign, Illinois. On the first day of August in Champaign, sunrise is at 5:51 am and sunset at 8:07 pm.
• Cicero - August »
  Cicero records an average high-temperature of a still warm 79°F (26.1°C) in August, closely mirroring the climate of the previous month. The month with the most sunshine in Cicero is August, with an average of 10.6h of sunshine.
• Bloomington - August »
  In August, summer persists in Bloomington featuring warm temperatures similar to the previous month. On the first day of August in Bloomington, sunrise is at 5:53 am and sunset at 8:11 pm.