Raccoon Creek State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Raccoon Creek State Park clear sky chart from 2005-11-06 to 2025-12-03.

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	16% 11% 4 9% 5% 5% 5% 4 5% 7% 31%	126635
	Night	16% 11% 4 9% 5% 4 4 3 5% 6% 32%	124048
Transparency	Day	51% 6% 10% 21% 11% 1	130241
	Night	52% 5% 10% 20% 11% 2	128511
Seeing	Day	23% 15% 27% 20% 11% 4	16076
	Night	22% 12% 26% 26% 12% 1	25841

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	16% 20% 7% 21% 4 3 3 2 3 4 16%	4056
	11th to 20th	Day	12% 21% 10% 16% 8% 6% 3 2 2 3 16%	4060
	21st to end	Day	21% 19% 6% 11% 8% 5% 4 3 4 4 16%	4466
February	1st to 10th	Day	19% 18% 6% 10% 6% 4 4 3 3 5% 24%	1800
	11th to 20th	Day	17% 14% 7% 13% 5% 5% 3 4 5% 5% 23%	1753
	21st to end	Day	19% 16% 4 10% 5% 4 3 4 4 4 27%	1660
March	1st to 10th	Day	17% 14% 6% 10% 4 4 4 3 4 6% 29%	4935
	11th to 20th	Day	12% 10% 4 8% 5% 6% 4 3 4 6% 38%	4980
	21st to end	Day	18% 10% 3 9% 5% 5% 4 4 5% 6% 31%	5465
April	1st to 10th	Day	16% 15% 3 8% 4 4 4 3 5% 7% 30%	2286
	11th to 20th	Day	17% 11% 3 7% 5% 5% 4 3 5% 5% 34%	2436
	21st to end	Day	21% 9% 3 6% 4 5% 4 3 5% 6% 34%	2600
May	1st to 10th	Day	22% 9% 3 8% 5% 5% 5% 5% 6% 6% 27%	5862
	11th to 20th	Day	19% 8% 3 8% 5% 4 5% 4 6% 8% 30%	5861
	21st to end	Day	19% 7% 2 6% 4 5% 5% 4 6% 9% 32%	6698
June	1st to 10th	Day	13% 7% 3 7% 5% 5% 6% 5% 6% 9% 35%	2800
	11th to 20th	Day	16% 7% 2 6% 5% 6% 4 4 6% 9% 35%	2800
	21st to end	Day	13% 6% 2 5% 5% 5% 5% 4 7% 10% 37%	2800
July	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 5% 6% 9% 41%	6041
	11th to 20th	Day	10% 7% 3 8% 5% 5% 6% 5% 7% 10% 34%	5900
	21st to end	Day	11% 7% 3 7% 5% 5% 5% 4 6% 8% 39%	6424
August	1st to 10th	Day	13% 7% 3 8% 6% 5% 6% 5% 6% 9% 32%	4234
	11th to 20th	Day	12% 6% 2 7% 4 5% 6% 4 7% 10% 36%	4174
	21st to end	Day	8% 4 2 6% 5% 7% 6% 5% 7% 9% 41%	4483
September	1st to 10th	Day	15% 6% 2 4 3 3 4 3 5% 7% 46%	2374
	11th to 20th	Day	11% 6% 2 6% 4 4 4 3 6% 9% 45%	2200
	21st to end	Day	20% 8% 3 7% 4 4 5% 4 4 6% 36%	2200
October	1st to 10th	Day	14% 6% 2 6% 4 3 5% 3 5% 8% 43%	2016
	11th to 20th	Day	19% 8% 3 6% 4 5% 5% 3 4 5% 37%	2000
	21st to end	Day	22% 11% 3 6% 4 4 4 3 5% 7% 33%	2200
November	1st to 10th	Day	11% 8% 2 6% 5% 5% 4 4 5% 6% 42%	1947
	11th to 20th	Day	17% 14% 4 8% 5% 4 4 3 5% 5% 31%	1790
	21st to end	Day	16% 16% 6% 9% 4 4 5% 3 5% 6% 25%	1680
December	1st to 10th	Day	19% 13% 5% 14% 6% 5% 4 3 4 5% 22%	2616
	11th to 20th	Day	23% 18% 6% 11% 4 3 2 2 3 4 22%	2990
	21st to end	Day	22% 20% 5% 13% 5% 4 4 2 5% 4 14%	4048
January	1st to 10th	Night	14% 18% 7% 23% 6% 4 3 2 3 3 15%	5889
	11th to 20th	Night	15% 17% 9% 15% 9% 5% 4 3 3 4 15%	5900
	21st to end	Night	21% 16% 6% 13% 7% 4 4 2 3 4 20%	6490
February	1st to 10th	Night	19% 16% 5% 11% 5% 3 3 4 4 5% 24%	2600
	11th to 20th	Night	19% 13% 5% 13% 5% 5% 4 3 4 5% 24%	2532
	21st to end	Night	20% 14% 5% 11% 6% 4 4 3 5% 5% 23%	1967
March	1st to 10th	Night	21% 13% 5% 9% 5% 3 3 2 3 5% 32%	4918
	11th to 20th	Night	13% 11% 4 7% 3 3 3 3 5% 7% 39%	4980
	21st to end	Night	17% 11% 3 9% 5% 5% 4 3 4 5% 35%	5467
April	1st to 10th	Night	19% 12% 3 7% 5% 5% 4 3 5% 6% 33%	2112
	11th to 20th	Night	17% 9% 3 7% 5% 4 5% 3 5% 7% 36%	1929
	21st to end	Night	16% 9% 3 7% 4 3 4 3 7% 7% 37%	1800
May	1st to 10th	Night	25% 11% 3 8% 4 4 4 4 5% 6% 25%	4033
	11th to 20th	Night	17% 8% 3 6% 4 4 4 3 5% 8% 37%	4032
	21st to end	Night	18% 7% 2 6% 4 4 5% 3 6% 8% 37%	4152
June	1st to 10th	Night	10% 6% 3 6% 5% 4 4 4 5% 9% 44%	1600
	11th to 20th	Night	12% 6% 2 6% 4 5% 4 4 6% 10% 41%	1600
	21st to end	Night	9% 4 2 5% 5% 5% 6% 4 6% 8% 45%	1600
July	1st to 10th	Night	11% 8% 2 7% 4 5% 4 4 6% 8% 42%	3910
	11th to 20th	Night	10% 7% 2 7% 5% 5% 5% 4 7% 10% 38%	4057
	21st to end	Night	8% 6% 2 8% 5% 5% 5% 4 6% 8% 44%	4427
August	1st to 10th	Night	12% 8% 3 7% 5% 5% 5% 5% 7% 8% 36%	2915
	11th to 20th	Night	12% 8% 2 7% 4 4 4 4 5% 7% 43%	2875
	21st to end	Night	8% 5% 2 6% 4 5% 6% 5% 6% 9% 44%	3380
September	1st to 10th	Night	13% 4 1 5% 3 4 3 4 5% 6% 51%	2022
	11th to 20th	Night	10% 4 1 4 3 3 4 3 4 9% 53%	2200
	21st to end	Night	17% 7% 3 6% 5% 4 4 4 5% 6% 40%	2200
October	1st to 10th	Night	14% 5% 2 6% 3 4 3 4 5% 6% 47%	2383
	11th to 20th	Night	16% 7% 2 7% 5% 4 5% 3 5% 5% 41%	2400
	21st to end	Night	23% 7% 3 6% 3 3 4 3 4 6% 38%	2640
November	1st to 10th	Night	13% 8% 3 5% 4 4 4 3 5% 6% 45%	2568
	11th to 20th	Night	19% 12% 3 7% 4 4 4 4 5% 6% 32%	2826
	21st to end	Night	20% 14% 4 8% 4 4 4 4 4 5% 28%	2940
December	1st to 10th	Night	16% 16% 9% 14% 5% 4 4 3 4 6% 18%	4609
	11th to 20th	Night	22% 17% 7% 10% 4 3 3 2 4 5% 22%	5205
	21st to end	Night	23% 19% 6% 10% 5% 4 4 3 4 5% 16%	6890

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	72% 5% 9% 9% 5%	4057
	11th to 20th	Day	76% 3 6% 9% 4 2	4060
	21st to end	Day	73% 3 8% 11% 5%	4466
February	1st to 10th	Day	65% 5% 9% 14% 7% 1	1800
	11th to 20th	Day	63% 5% 8% 16% 7%	1762
	21st to end	Day	61% 4 11% 16% 7% 2	1660
March	1st to 10th	Day	56% 5% 9% 23% 7% 1	4935
	11th to 20th	Day	47% 4 10% 27% 9% 2	4980
	21st to end	Day	53% 4 8% 20% 13% 1	5465
April	1st to 10th	Day	53% 6% 9% 18% 11% 2	2286
	11th to 20th	Day	50% 6% 10% 18% 14% 2	2436
	21st to end	Day	50% 6% 9% 22% 11% 2	2600
May	1st to 10th	Day	54% 7% 9% 17% 9% 3	5897
	11th to 20th	Day	50% 7% 10% 22% 10% 1	5865
	21st to end	Day	47% 7% 12% 21% 10% 3	6713
June	1st to 10th	Day	44% 8% 13% 21% 12% 1	2800
	11th to 20th	Day	45% 8% 12% 22% 12% 1	2800
	21st to end	Day	41% 8% 13% 24% 14% 1	2800
July	1st to 10th	Day	38% 7% 11% 26% 16% 2	5976
	11th to 20th	Day	43% 8% 13% 24% 12%	5831
	21st to end	Day	41% 6% 10% 23% 18% 1	6240
August	1st to 10th	Day	47% 8% 13% 23% 10%	4221
	11th to 20th	Day	41% 7% 12% 29% 11%	4213
	21st to end	Day	37% 7% 12% 28% 13% 2	4483
September	1st to 10th	Day	38% 6% 10% 23% 20% 3	2374
	11th to 20th	Day	35% 6% 14% 27% 16% 2	2200
	21st to end	Day	49% 5% 9% 22% 15%	2200
October	1st to 10th	Day	32% 4 9% 32% 22% 1	3276
	11th to 20th	Day	44% 5% 11% 21% 15% 5%	3240
	21st to end	Day	38% 4 12% 27% 18% 1	3538
November	1st to 10th	Day	42% 5% 12% 22% 17% 2	1947
	11th to 20th	Day	55% 4 9% 20% 10% 2	1790
	21st to end	Day	59% 6% 10% 16% 7% 1	1680
December	1st to 10th	Day	65% 5% 13% 13% 4	2616
	11th to 20th	Day	67% 3 11% 14% 5%	2986
	21st to end	Day	73% 4 9% 11% 4	4048
January	1st to 10th	Night	74% 4 7% 11% 4	5889
	11th to 20th	Night	74% 4 8% 10% 4 1	5900
	21st to end	Night	70% 3 9% 12% 5% 1	6490
February	1st to 10th	Night	63% 5% 8% 17% 7%	2600
	11th to 20th	Night	63% 4 9% 17% 7% 1	2534
	21st to end	Night	63% 4 8% 15% 10% 1	1967
March	1st to 10th	Night	56% 3 9% 22% 9% 1	4918
	11th to 20th	Night	43% 4 12% 28% 9% 3	4980
	21st to end	Night	52% 5% 10% 18% 14% 2	5467
April	1st to 10th	Night	52% 5% 10% 19% 12% 2	2112
	11th to 20th	Night	47% 6% 11% 17% 15% 3	1929
	21st to end	Night	45% 5% 11% 22% 14% 3	1800
May	1st to 10th	Night	59% 7% 8% 14% 9% 4	4060
	11th to 20th	Night	46% 8% 9% 25% 12% 1	4033
	21st to end	Night	44% 8% 11% 24% 10% 3	4159
June	1st to 10th	Night	37% 9% 11% 24% 17% 2	1600
	11th to 20th	Night	39% 7% 14% 23% 15% 2	1600
	21st to end	Night	36% 9% 12% 24% 17% 2	1600
July	1st to 10th	Night	41% 5% 9% 25% 18% 2	3867
	11th to 20th	Night	40% 8% 17% 23% 12% 1	4006
	21st to end	Night	37% 7% 11% 20% 23% 2	4297
August	1st to 10th	Night	44% 9% 12% 23% 11% 1	2904
	11th to 20th	Night	40% 6% 9% 26% 17% 1	2902
	21st to end	Night	35% 7% 12% 30% 13% 2	3380
September	1st to 10th	Night	33% 6% 10% 25% 21% 5%	2022
	11th to 20th	Night	29% 6% 13% 28% 23% 1	2200
	21st to end	Night	45% 5% 10% 21% 18% 1	2200
October	1st to 10th	Night	34% 4 8% 27% 25% 2	3903
	11th to 20th	Night	38% 5% 11% 23% 16% 8%	3899
	21st to end	Night	35% 4 9% 29% 22% 2	4252
November	1st to 10th	Night	40% 4 11% 24% 18% 3	2568
	11th to 20th	Night	53% 4 10% 20% 11% 3	2826
	21st to end	Night	58% 4 10% 21% 6% 1	2940
December	1st to 10th	Night	68% 4 10% 15% 3	4609
	11th to 20th	Night	67% 3 14% 13% 3	5208
	21st to end	Night	70% 5% 9% 13% 3	6890

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	36% 26% 24% 10% 4	300
	11th to 20th	Day	37% 29% 26% 7% 1	300
	21st to end	Day	32% 32% 27% 5% 3	330
February	1st to 10th	Day	36% 24% 32% 7% 1	300
	11th to 20th	Day	38% 30% 25% 5% 1	300
	21st to end	Day	38% 28% 27% 7%	260
March	1st to 10th	Day	30% 22% 30% 16% 3	500
	11th to 20th	Day	32% 21% 30% 12% 5% 1	500
	21st to end	Day	32% 22% 27% 14% 3	550
April	1st to 10th	Day	34% 19% 25% 14% 6% 1	500
	11th to 20th	Day	27% 21% 27% 15% 7% 3	492
	21st to end	Day	29% 17% 32% 15% 6% 1	500
May	1st to 10th	Day	28% 21% 26% 16% 6% 3	503
	11th to 20th	Day	21% 16% 33% 18% 8% 4	527
	21st to end	Day	18% 11% 27% 22% 16% 6%	573
June	1st to 10th	Day	15% 10% 33% 26% 14% 3	530
	11th to 20th	Day	19% 12% 24% 28% 14% 3	530
	21st to end	Day	12% 12% 31% 26% 16% 3	530
July	1st to 10th	Day	13% 7% 22% 28% 21% 10%	525
	11th to 20th	Day	12% 7% 28% 27% 19% 7%	524
	21st to end	Day	11% 9% 24% 32% 18% 7%	576
August	1st to 10th	Day	12% 8% 23% 31% 18% 8%	526
	11th to 20th	Day	14% 8% 21% 28% 19% 9%	519
	21st to end	Day	11% 5% 24% 27% 21% 10%	583
September	1st to 10th	Day	18% 9% 20% 26% 21% 7%	530
	11th to 20th	Day	11% 5% 19% 30% 23% 12%	530
	21st to end	Day	24% 11% 25% 23% 14% 4	530
October	1st to 10th	Day	16% 10% 28% 24% 16% 5%	530
	11th to 20th	Day	22% 18% 28% 22% 8% 2	530
	21st to end	Day	28% 17% 31% 17% 6%	583
November	1st to 10th	Day	22% 16% 34% 16% 9% 2	425
	11th to 20th	Day	36% 16% 28% 14% 5% 1	278
	21st to end	Day	32% 21% 36% 10% 1	220
December	1st to 10th	Day	30% 28% 27% 10% 3 1	204
	11th to 20th	Day	32% 23% 34% 10% 2	200
	21st to end	Day	35% 25% 26% 11% 3	238
January	1st to 10th	Night	30% 20% 34% 15% 2	800
	11th to 20th	Night	32% 19% 31% 15% 3	800
	21st to end	Night	28% 22% 29% 18% 3	880
February	1st to 10th	Night	32% 17% 29% 20% 3	800
	11th to 20th	Night	30% 21% 33% 14% 1	783
	21st to end	Night	28% 20% 32% 17% 2	660
March	1st to 10th	Night	27% 18% 31% 22% 3	800
	11th to 20th	Night	27% 18% 27% 22% 5% 1	800
	21st to end	Night	27% 16% 32% 20% 4	880
April	1st to 10th	Night	26% 17% 29% 22% 6%	800
	11th to 20th	Night	23% 15% 31% 22% 9% 1	745
	21st to end	Night	20% 11% 34% 29% 6%	600
May	1st to 10th	Night	23% 10% 26% 32% 8% 2	600
	11th to 20th	Night	20% 8% 28% 29% 14% 1	591
	21st to end	Night	13% 3 24% 35% 22% 3	536
June	1st to 10th	Night	11% 5% 25% 42% 17%	400
	11th to 20th	Night	14% 5% 24% 38% 19% 1	400
	21st to end	Night	10% 4 28% 34% 24% 1	400
July	1st to 10th	Night	8% 3 18% 40% 24% 6%	515
	11th to 20th	Night	9% 3 21% 36% 26% 4	582
	21st to end	Night	11% 4 14% 42% 27% 2	657
August	1st to 10th	Night	10% 2 17% 40% 28% 3	597
	11th to 20th	Night	11% 4 12% 39% 29% 4	594
	21st to end	Night	11% 5% 19% 31% 29% 5%	752
September	1st to 10th	Night	15% 4 19% 34% 25% 4	800
	11th to 20th	Night	11% 4 15% 36% 30% 4	800
	21st to end	Night	19% 8% 23% 26% 21% 3	800
October	1st to 10th	Night	16% 8% 23% 30% 22% 2	800
	11th to 20th	Night	21% 12% 30% 25% 11% 1	800
	21st to end	Night	27% 13% 27% 25% 7%	880
November	1st to 10th	Night	18% 13% 28% 29% 12%	820
	11th to 20th	Night	30% 14% 27% 22% 6% 1	840
	21st to end	Night	30% 15% 30% 20% 6%	840
December	1st to 10th	Night	32% 20% 26% 18% 4	809
	11th to 20th	Night	29% 19% 29% 19% 3	800
	21st to end	Night	31% 17% 30% 20% 2	880

Page generated at 2025-11-30 01:00:52. Version ac07

Copyright © 2025 Attilla Danko.