Fall Creek Falls State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fall Creek Falls State Park clear sky chart from 2005-11-06 to 2025-07-21.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	13% 8% 3 8% 5% 5% 5% 4 6% 7% 37%	120089
	Night	13% 9% 4 7% 4 4 4 3 5% 7% 40%	119033
Transparency	Day	44% 6% 10% 21% 15% 4	123854
	Night	42% 5% 10% 21% 17% 5%	123404
Seeing	Day	19% 13% 25% 21% 15% 7%	15576
	Night	17% 11% 22% 28% 18% 4	25597

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	13% 11% 8% 11% 5% 4 4 4 5% 4 31%	4056
	11th to 20th	Day	15% 7% 4 16% 4 2 3 2 3 4 39%	4060
	21st to end	Day	18% 11% 5% 7% 4 3 3 3 4 6% 36%	4696
February	1st to 10th	Day	17% 11% 4 9% 5% 4 4 3 4 5% 34%	2000
	11th to 20th	Day	20% 10% 6% 8% 5% 4 3 3 4 5% 31%	1948
	21st to end	Day	19% 9% 3 8% 5% 4 4 3 4 6% 35%	1650
March	1st to 10th	Day	17% 11% 4 8% 5% 4 4 3 5% 6% 32%	4480
	11th to 20th	Day	12% 8% 3 7% 4 4 4 3 5% 5% 45%	4948
	21st to end	Day	13% 9% 3 7% 4 4 4 3 5% 6% 41%	5465
April	1st to 10th	Day	12% 8% 3 6% 5% 4 5% 4 7% 6% 40%	2395
	11th to 20th	Day	13% 9% 4 5% 5% 3 4 3 5% 7% 43%	2374
	21st to end	Day	13% 8% 3 8% 5% 4 5% 4 6% 7% 38%	2525
May	1st to 10th	Day	17% 10% 3 8% 5% 5% 5% 5% 7% 7% 28%	5862
	11th to 20th	Day	16% 10% 3 10% 7% 6% 5% 4 6% 7% 27%	5861
	21st to end	Day	15% 9% 3 8% 4 5% 4 4 5% 7% 36%	6433
June	1st to 10th	Day	9% 6% 3 7% 6% 6% 5% 5% 6% 9% 37%	2600
	11th to 20th	Day	5% 5% 2 7% 6% 7% 6% 5% 7% 10% 40%	2600
	21st to end	Day	6% 5% 2 7% 6% 6% 6% 6% 9% 11% 36%	2600
July	1st to 10th	Day	7% 5% 2 8% 7% 7% 7% 6% 9% 11% 32%	4250
	11th to 20th	Day	11% 7% 3 7% 7% 6% 6% 5% 7% 10% 32%	4250
	21st to end	Day	16% 11% 4 10% 7% 7% 7% 6% 5% 6% 19%	4466
August	1st to 10th	Day	5% 5% 2 6% 5% 6% 6% 5% 9% 10% 42%	4089
	11th to 20th	Day	6% 5% 2 8% 6% 6% 6% 5% 8% 12% 36%	3729
	21st to end	Day	7% 5% 2 6% 5% 5% 7% 5% 6% 7% 45%	4180
September	1st to 10th	Day	11% 6% 3 7% 6% 6% 7% 4 6% 7% 36%	2176
	11th to 20th	Day	13% 8% 2 8% 5% 5% 4 3 6% 8% 38%	2090
	21st to end	Day	13% 5% 2 7% 5% 4 5% 3 6% 7% 43%	2090
October	1st to 10th	Day	10% 6% 2 5% 3 4 4 4 5% 5% 52%	2090
	11th to 20th	Day	12% 6% 2 5% 3 2 4 3 5% 6% 53%	2028
	21st to end	Day	14% 7% 2 5% 3 4 4 3 5% 6% 47%	1967
November	1st to 10th	Day	10% 6% 2 5% 4 4 3 3 4 5% 53%	1762
	11th to 20th	Day	12% 9% 2 6% 3 3 4 4 5% 6% 45%	1800
	21st to end	Day	13% 9% 2 7% 4 4 4 3 5% 6% 42%	1800
December	1st to 10th	Day	14% 9% 3 7% 4 4 4 3 5% 5% 42%	2930
	11th to 20th	Day	15% 14% 6% 11% 5% 4 4 3 5% 4 29%	3373
	21st to end	Day	16% 11% 6% 7% 5% 4 4 3 6% 7% 31%	4466
January	1st to 10th	Night	13% 12% 5% 11% 4 3 3 3 4 4 36%	5889
	11th to 20th	Night	17% 9% 4 7% 6% 5% 3 2 3 3 40%	5900
	21st to end	Night	16% 11% 5% 7% 4 4 3 3 4 5% 38%	6243
February	1st to 10th	Night	16% 9% 5% 9% 5% 3 4 3 5% 6% 34%	2400
	11th to 20th	Night	21% 11% 3 8% 5% 4 4 3 4 4 32%	2338
	21st to end	Night	21% 11% 4 6% 4 4 3 3 6% 5% 33%	1980
March	1st to 10th	Night	17% 12% 5% 8% 4 4 4 3 5% 6% 30%	5373
	11th to 20th	Night	11% 7% 2 5% 4 3 4 4 6% 6% 47%	5010
	21st to end	Night	14% 8% 4 8% 5% 4 4 3 4 5% 40%	5467
April	1st to 10th	Night	11% 8% 2 6% 4 4 5% 4 6% 7% 44%	2020
	11th to 20th	Night	12% 8% 2 5% 4 2 3 3 5% 7% 47%	1975
	21st to end	Night	12% 7% 2 6% 5% 4 4 3 6% 8% 44%	1875
May	1st to 10th	Night	12% 9% 4 9% 5% 5% 6% 4 7% 8% 30%	4033
	11th to 20th	Night	18% 11% 4 8% 5% 5% 5% 4 5% 7% 29%	4032
	21st to end	Night	13% 7% 2 8% 5% 4 5% 4 6% 9% 36%	4421
June	1st to 10th	Night	6% 6% 3 9% 6% 5% 5% 5% 6% 8% 41%	1800
	11th to 20th	Night	4 3 1 4 4 4 5% 5% 8% 12% 50%	1800
	21st to end	Night	5% 5% 2 5% 5% 5% 6% 5% 6% 11% 44%	1800
July	1st to 10th	Night	7% 5% 3 6% 5% 5% 6% 6% 9% 10% 38%	2930
	11th to 20th	Night	8% 5% 2 6% 4 4 4 4 7% 11% 45%	2930
	21st to end	Night	13% 10% 4 10% 7% 6% 6% 5% 7% 9% 24%	3087
August	1st to 10th	Night	3 4 2 5% 4 4 5% 4 7% 11% 51%	2825
	11th to 20th	Night	5% 4 3 8% 4 5% 5% 4 7% 10% 46%	3097
	21st to end	Night	5% 3 2 4 4 4 4 4 6% 8% 57%	3476
September	1st to 10th	Night	10% 6% 3 5% 4 4 5% 3 6% 7% 46%	1985
	11th to 20th	Night	10% 8% 3 6% 5% 4 4 3 6% 7% 43%	2090
	21st to end	Night	10% 5% 2 7% 4 3 3 3 5% 5% 52%	2090
October	1st to 10th	Night	10% 4 2 4 3 3 2 3 4 6% 59%	2090
	11th to 20th	Night	13% 5% 2 6% 3 3 3 3 5% 4 52%	2152
	21st to end	Night	12% 8% 2 5% 4 3 3 3 4 5% 50%	2627
November	1st to 10th	Night	12% 7% 2 6% 4 3 4 2 5% 5% 50%	2536
	11th to 20th	Night	11% 10% 3 5% 3 3 3 3 5% 6% 46%	2600
	21st to end	Night	14% 10% 3 7% 4 3 3 4 5% 5% 42%	2600
December	1st to 10th	Night	15% 10% 4 9% 5% 4 4 3 4 5% 38%	4250
	11th to 20th	Night	18% 14% 6% 7% 4 3 3 2 3 4 34%	4822
	21st to end	Night	14% 12% 7% 9% 5% 5% 5% 3 5% 7% 29%	6490

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	53% 4 7% 19% 15% 2	4057
	11th to 20th	Day	49% 3 5% 15% 26% 2	4060
	21st to end	Day	49% 2 7% 23% 13% 5%	4696
February	1st to 10th	Day	53% 3 8% 17% 17% 2	2000
	11th to 20th	Day	54% 4 7% 17% 14% 4	1958
	21st to end	Day	51% 4 8% 15% 18% 6%	1650
March	1st to 10th	Day	51% 7% 6% 12% 16% 9%	4480
	11th to 20th	Day	40% 4 7% 19% 21% 10%	4948
	21st to end	Day	44% 5% 9% 27% 14% 1	5465
April	1st to 10th	Day	43% 5% 11% 22% 17% 3	2395
	11th to 20th	Day	40% 5% 7% 20% 23% 4	2374
	21st to end	Day	43% 6% 10% 26% 14% 1	2525
May	1st to 10th	Day	51% 9% 11% 21% 8% 1	5897
	11th to 20th	Day	54% 8% 13% 18% 7%	5865
	21st to end	Day	46% 7% 9% 22% 14% 2	6447
June	1st to 10th	Day	41% 9% 14% 22% 13% 2	2600
	11th to 20th	Day	36% 8% 19% 22% 14% 2	2600
	21st to end	Day	37% 11% 18% 19% 13% 3	2600
July	1st to 10th	Day	39% 12% 20% 19% 8% 1	4185
	11th to 20th	Day	43% 9% 18% 22% 6% 2	4181
	21st to end	Day	62% 9% 10% 14% 4 1	4324
August	1st to 10th	Day	31% 11% 16% 31% 11% 1	4076
	11th to 20th	Day	37% 8% 19% 22% 14% 1	3765
	21st to end	Day	34% 8% 11% 33% 13% 1	4179
September	1st to 10th	Day	44% 8% 12% 17% 15% 5%	2176
	11th to 20th	Day	44% 6% 10% 21% 18% 2	2090
	21st to end	Day	39% 6% 10% 22% 18% 5%	2090
October	1st to 10th	Day	25% 4 7% 18% 35% 12%	3480
	11th to 20th	Day	23% 3 5% 23% 31% 14%	3346
	21st to end	Day	29% 4 9% 23% 25% 10%	3217
November	1st to 10th	Day	34% 5% 7% 24% 25% 6%	1762
	11th to 20th	Day	40% 4 5% 23% 23% 6%	1800
	21st to end	Day	43% 4 7% 21% 21% 4	1800
December	1st to 10th	Day	43% 4 5% 21% 24% 3	2930
	11th to 20th	Day	58% 3 6% 18% 12% 2	3370
	21st to end	Day	51% 4 11% 20% 11% 2	4466
January	1st to 10th	Night	50% 3 8% 19% 17% 2	5889
	11th to 20th	Night	49% 3 6% 15% 21% 6%	5900
	21st to end	Night	49% 3 6% 16% 20% 7%	6243
February	1st to 10th	Night	50% 3 10% 19% 15% 3	2400
	11th to 20th	Night	55% 3 7% 16% 13% 5%	2339
	21st to end	Night	52% 3 8% 17% 15% 5%	1980
March	1st to 10th	Night	52% 6% 7% 13% 18% 5%	5373
	11th to 20th	Night	35% 4 7% 20% 18% 14%	5010
	21st to end	Night	46% 4 8% 26% 14% 2	5467
April	1st to 10th	Night	39% 5% 11% 22% 20% 3	2020
	11th to 20th	Night	36% 4 9% 23% 23% 5%	1975
	21st to end	Night	38% 6% 12% 29% 14% 1	1875
May	1st to 10th	Night	47% 11% 14% 20% 8% 1	4060
	11th to 20th	Night	54% 7% 13% 17% 9%	4033
	21st to end	Night	41% 10% 12% 23% 12% 1	4429
June	1st to 10th	Night	38% 7% 15% 25% 12% 2	1800
	11th to 20th	Night	25% 8% 21% 30% 15% 2	1800
	21st to end	Night	32% 9% 17% 27% 12% 4	1800
July	1st to 10th	Night	36% 11% 21% 22% 8% 2	2885
	11th to 20th	Night	31% 9% 21% 29% 7% 3	2876
	21st to end	Night	55% 9% 13% 15% 6% 1	2988
August	1st to 10th	Night	25% 8% 14% 38% 14% 1	2814
	11th to 20th	Night	31% 9% 23% 23% 14% 1	3127
	21st to end	Night	23% 8% 13% 38% 17% 1	3476
September	1st to 10th	Night	36% 7% 14% 21% 16% 5%	1985
	11th to 20th	Night	39% 7% 11% 20% 21% 2	2090
	21st to end	Night	34% 5% 10% 24% 23% 5%	2090
October	1st to 10th	Night	21% 4 7% 24% 29% 15%	3480
	11th to 20th	Night	22% 3 6% 22% 29% 18%	3573
	21st to end	Night	26% 3 7% 25% 27% 12%	4327
November	1st to 10th	Night	36% 4 7% 22% 24% 8%	2536
	11th to 20th	Night	38% 3 7% 19% 26% 7%	2600
	21st to end	Night	44% 3 6% 23% 20% 5%	2600
December	1st to 10th	Night	50% 4 5% 15% 24% 3	4250
	11th to 20th	Night	54% 2 5% 18% 18% 2	4824
	21st to end	Night	53% 5% 9% 21% 11% 1	6490

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	30% 28% 32% 9% 2	300
	11th to 20th	Day	37% 27% 22% 10% 3 1	300
	21st to end	Day	26% 30% 34% 7% 2	330
February	1st to 10th	Day	28% 28% 30% 10% 3	300
	11th to 20th	Day	44% 25% 25% 4 1 1	300
	21st to end	Day	41% 23% 28% 7% 1	249
March	1st to 10th	Day	32% 24% 31% 10% 2	300
	11th to 20th	Day	29% 22% 28% 17% 3 1	481
	21st to end	Day	27% 21% 32% 14% 5% 1	550
April	1st to 10th	Day	24% 20% 28% 18% 9% 1	500
	11th to 20th	Day	22% 19% 30% 20% 7% 1	492
	21st to end	Day	22% 14% 32% 18% 11% 2	500
May	1st to 10th	Day	20% 16% 33% 17% 10% 4	503
	11th to 20th	Day	15% 11% 31% 22% 14% 7%	527
	21st to end	Day	17% 9% 22% 26% 15% 12%	573
June	1st to 10th	Day	13% 8% 22% 26% 21% 10%	530
	11th to 20th	Day	7% 5% 20% 28% 23% 16%	530
	21st to end	Day	9% 5% 20% 27% 23% 16%	530
July	1st to 10th	Day	12% 3 14% 28% 25% 17%	525
	11th to 20th	Day	9% 5% 14% 22% 29% 21%	524
	21st to end	Day	13% 3 15% 24% 26% 19%	532
August	1st to 10th	Day	11% 5% 17% 26% 25% 17%	486
	11th to 20th	Day	11% 4 16% 32% 28% 10%	479
	21st to end	Day	14% 3 11% 25% 30% 18%	539
September	1st to 10th	Day	11% 5% 15% 26% 31% 12%	490
	11th to 20th	Day	15% 5% 15% 26% 30% 10%	490
	21st to end	Day	17% 7% 17% 28% 24% 7%	490
October	1st to 10th	Day	14% 6% 21% 32% 20% 7%	490
	11th to 20th	Day	14% 14% 28% 27% 14% 2	490
	21st to end	Day	20% 12% 31% 23% 11% 3	416
November	1st to 10th	Day	19% 12% 35% 24% 8% 2	300
	11th to 20th	Day	20% 18% 38% 20% 3	300
	21st to end	Day	24% 16% 37% 14% 7% 1	300
December	1st to 10th	Day	30% 20% 33% 13% 4 1	300
	11th to 20th	Day	28% 19% 31% 16% 5% 1	300
	21st to end	Day	30% 21% 31% 13% 4 1	330
January	1st to 10th	Night	26% 21% 28% 21% 5%	800
	11th to 20th	Night	28% 22% 25% 21% 4	800
	21st to end	Night	23% 19% 33% 22% 2	880
February	1st to 10th	Night	23% 18% 31% 25% 4	800
	11th to 20th	Night	29% 21% 29% 20% 1	783
	21st to end	Night	31% 19% 29% 20% 1	660
March	1st to 10th	Night	23% 17% 31% 25% 5%	800
	11th to 20th	Night	21% 17% 31% 24% 6% 1	800
	21st to end	Night	21% 15% 31% 25% 8%	880
April	1st to 10th	Night	19% 15% 29% 27% 10%	620
	11th to 20th	Night	17% 12% 33% 26% 11% 1	593
	21st to end	Night	17% 8% 29% 33% 12% 1	600
May	1st to 10th	Night	14% 9% 29% 30% 15% 3	600
	11th to 20th	Night	14% 6% 23% 31% 22% 5%	591
	21st to end	Night	9% 5% 16% 34% 30% 6%	650
June	1st to 10th	Night	9% 4 15% 34% 32% 6%	600
	11th to 20th	Night	4 2 14% 34% 36% 9%	600
	21st to end	Night	7% 2 10% 34% 37% 11%	600
July	1st to 10th	Night	10% 3 7% 26% 44% 11%	585
	11th to 20th	Night	8% 3 6% 28% 41% 14%	582
	21st to end	Night	8% 1 7% 30% 41% 13%	624
August	1st to 10th	Night	6% 2 8% 28% 47% 9%	567
	11th to 20th	Night	7% 2 9% 37% 39% 6%	564
	21st to end	Night	9% 1 6% 30% 42% 11%	627
September	1st to 10th	Night	12% 3 9% 30% 38% 8%	655
	11th to 20th	Night	14% 5% 14% 27% 34% 7%	760
	21st to end	Night	13% 4 14% 32% 32% 4	760
October	1st to 10th	Night	12% 6% 17% 30% 26% 9%	760
	11th to 20th	Night	17% 10% 24% 28% 20% 2	760
	21st to end	Night	16% 10% 23% 34% 15% 2	836
November	1st to 10th	Night	16% 10% 21% 33% 17% 3	780
	11th to 20th	Night	16% 17% 28% 27% 11% 1	800
	21st to end	Night	22% 16% 24% 28% 11% 1	800
December	1st to 10th	Night	25% 18% 26% 25% 6%	800
	11th to 20th	Night	23% 16% 25% 28% 7% 1	800
	21st to end	Night	27% 17% 25% 26% 5%	880

Page generated at 2025-07-18 00:10:00. Version ac07

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