2025 Compare Climate & Weather:
Greencastle, PA vs Decatur, IL

Highlights

On average, there are 199 sunny days per year in Decatur. Greencastle averages 197 sunny days per year. The US average is 205 sunny days.

Decatur, Illinois gets 39.5 inches of rain, on average, per year. Greencastle, Pennsylvania gets 41.1 inches of rain, on average, per year. The US average is 38.1 inches of rain per year.

Decatur averages 13 inches of snow per year. Greencastle averages 29.3 inches of snow per year. The US average is 27.8 inches of snow per year.

Weather Highlights

Decatur, Illinois
Summer High: the July high is around 86.9 degrees
Winter Low: the January low is 18.8
Rain: averages 39.5 inches of rain a year
Snow: averages 13 inches of snow a year

Greencastle, Pennsylvania
Summer High: the July high is around 85.4 degrees
Winter Low: the January low is 22.4
Rain: averages 41.1 inches of rain a year
Snow: averages 29.3 inches of snow a year

BestPlaces Comfort Index

The annual BestPlaces Comfort Index for Decatur is 7.2 (10=best), which means it is one of the most pleasant places in Illinois.

The annual BestPlaces Comfort Index for Greencastle is 7.2 (10=best), which means it is one of the most pleasant places in Pennsylvania.

Today's Weather - Greencastle, PA

54°F

Today's Weather - Decatur, IL

58°F

Average Monthly High / Low (°F)

Hot, Freezing, Rainy, Snowy Days: Greencastle / Decatur

July is the hottest month for Greencastle with an average high temperature of 85.4°, which ranks it as warmer than most places in Pennsylvania. In Greencastle, there are 4 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Greencastle are September, June and August.

July is the hottest month for Decatur with an average high temperature of 86.9°, which ranks it as warmer than most places in Illinois. In Decatur, there are 3 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Decatur are September, May and June.

January has the coldest nighttime temperatures for Greencastle with an average of 22.4°. This is one of the warmest places in Pennsylvania.

January has the coldest nighttime temperatures for Decatur with an average of 18.8°. This is warmer than most places in Illinois.

In Greencastle, there are 15.5 days annually when the high temperature is over 90°, which is hotter than most places in Pennsylvania.

In Decatur, there are 24.8 days annually when the high temperature is over 90°, which is hotter than most places in Illinois.

In Greencastle, there are 107.6 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in Pennsylvania.

In Decatur, there are 112.5 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in Illinois.

In Greencastle, there are 0.7 days annually when the nighttime low temperature falls below zero°, which is warmer than most places in Pennsylvania.

In Decatur, there are 4.8 days annually when the nighttime low temperature falls below zero°, which is warmer than most places in Illinois.

May is the wettest month in Greencastle with 4.1 inches of rain, and the driest month is February with 2.7 inches. The wettest season is Summer with 28% of yearly precipitation and 21% occurs in Spring, which is the driest season. The annual rainfall of 41.1 inches in Greencastle means that it is drier than most places in Pennsylvania.


June is the wettest month in Decatur with 4.5 inches of rain, and the driest month is January with 1.9 inches. The wettest season is Autumn with 31% of yearly precipitation and 16% occurs in Spring, which is the driest season. The annual rainfall of 39.5 inches in Decatur means that it is about average compared to other places in Illinois.

May is the rainiest month in Greencastle with 12.3 days of rain, and October is the driest month with only 8.4 rainy days. There are 119.4 rainy days annually in Greencastle, which is less rainy than most places in Pennsylvania. The rainiest season is Summer when it rains 28% of the time and the driest is Winter with only a 22% chance of a rainy day.

May is the rainiest month in Decatur with 11.5 days of rain, and September is the driest month with only 6.9 rainy days. There are 104.3 rainy days annually in Decatur, which is less rainy than most places in Illinois. The rainiest season is Summer when it rains 30% of the time and the driest is Spring with only a 23% chance of a rainy day.

An annual snowfall of 29.3 inches in Greencastle means that it is about average compared to other places in Pennsylvania.

An annual snowfall of 13.0 inches in Decatur means that it is less snowy than most places in Illinois.

February is the snowiest month in Greencastle with 10.1 inches of snow, and 6 months of the year have significant snowfall.

January is the snowiest month in Decatur with 4.2 inches of snow, and 4 months of the year have significant snowfall.