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 2024-05-15.

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	17% 11% 4 8% 5% 5% 4 4 5% 7% 31%	83687
	Night	17% 12% 4 8% 5% 4 4 3 5% 6% 32%	85847
Transparency	Day	52% 6% 11% 19% 10% 1	83408
	Night	52% 6% 10% 20% 11% 2	85645
Seeing	Day	23% 15% 27% 20% 11% 4	14011
	Night	22% 12% 26% 26% 12% 1	23885

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	19% 21% 8% 11% 4 3 3 3 3 5% 19%	2836
	11th to 20th	Day	13% 23% 9% 13% 6% 4 3 3 3 4 18%	2840
	21st to end	Day	25% 21% 7% 12% 6% 4 3 2 3 3 13%	3124
February	1st to 10th	Day	19% 18% 5% 10% 6% 4 4 3 3 5% 24%	1710
	11th to 20th	Day	16% 14% 7% 13% 5% 5% 3 3 5% 5% 23%	1663
	21st to end	Day	19% 16% 4 10% 5% 4 3 3 4 4 27%	1579
March	1st to 10th	Day	21% 14% 5% 8% 4 4 4 3 4 6% 27%	3435
	11th to 20th	Day	13% 11% 4 9% 5% 6% 5% 3 4 6% 34%	3480
	21st to end	Day	21% 10% 3 8% 4 4 4 4 5% 6% 32%	3815
April	1st to 10th	Day	15% 15% 3 8% 4 4 4 3 5% 7% 31%	2171
	11th to 20th	Day	18% 11% 3 6% 5% 5% 4 3 5% 5% 34%	2313
	21st to end	Day	22% 9% 3 6% 4 5% 4 3 5% 6% 33%	2470
May	1st to 10th	Day	21% 10% 3 7% 5% 5% 5% 4 6% 6% 29%	2470
	11th to 20th	Day	21% 8% 3 8% 6% 4 5% 5% 5% 7% 29%	2353
	21st to end	Day	12% 6% 2 5% 5% 5% 6% 5% 7% 11% 36%	2629
June	1st to 10th	Day	13% 8% 3 7% 5% 5% 6% 5% 6% 9% 34%	2520
	11th to 20th	Day	16% 7% 2 6% 5% 5% 4 4 6% 9% 35%	2520
	21st to end	Day	14% 6% 2 6% 5% 5% 5% 4 7% 10% 37%	2520
July	1st to 10th	Day	11% 7% 3 6% 5% 5% 6% 5% 6% 8% 39%	2397
	11th to 20th	Day	12% 7% 2 7% 5% 5% 5% 5% 6% 9% 37%	2340
	21st to end	Day	12% 6% 3 6% 6% 6% 5% 5% 7% 9% 35%	2547
August	1st to 10th	Day	11% 6% 2 7% 6% 5% 7% 6% 7% 10% 35%	2327
	11th to 20th	Day	13% 5% 2 8% 4 6% 6% 4 7% 10% 34%	2303
	21st to end	Day	12% 6% 2 7% 5% 7% 5% 4 7% 8% 38%	2472
September	1st to 10th	Day	17% 6% 2 5% 3 4 4 3 5% 7% 44%	2138
	11th to 20th	Day	12% 6% 2 6% 4 4 4 3 6% 9% 44%	1980
	21st to end	Day	18% 7% 3 7% 4 4 5% 4 4 6% 39%	1980
October	1st to 10th	Day	15% 7% 3 6% 4 4 5% 4 6% 8% 39%	1815
	11th to 20th	Day	20% 9% 3 7% 4 5% 5% 3 4 5% 35%	1800
	21st to end	Day	24% 12% 3 6% 4 4 4 3 5% 6% 31%	1980
November	1st to 10th	Day	11% 9% 3 6% 5% 5% 5% 4 4 6% 42%	1758
	11th to 20th	Day	17% 14% 4 7% 5% 4 4 3 5% 5% 32%	1620
	21st to end	Day	16% 16% 6% 8% 4 5% 6% 3 5% 6% 26%	1520
December	1st to 10th	Day	21% 18% 7% 11% 5% 4 4 4 4 5% 18%	1520
	11th to 20th	Day	19% 18% 7% 12% 5% 4 3 3 4 6% 20%	1910
	21st to end	Day	25% 22% 6% 11% 5% 3 4 2 5% 4 13%	2832
January	1st to 10th	Night	16% 21% 8% 12% 5% 5% 4 3 4 4 19%	4109
	11th to 20th	Night	18% 18% 8% 13% 6% 5% 4 3 4 4 16%	4120
	21st to end	Night	28% 17% 7% 12% 6% 3 3 2 3 3 16%	4532
February	1st to 10th	Night	19% 16% 4 11% 5% 3 3 4 4 4 25%	2470
	11th to 20th	Night	18% 13% 5% 13% 5% 4 4 3 4 5% 25%	2403
	21st to end	Night	20% 14% 5% 11% 6% 4 4 3 5% 5% 24%	1872
March	1st to 10th	Night	23% 13% 4 7% 4 3 3 2 4 6% 33%	3418
	11th to 20th	Night	17% 13% 6% 8% 3 3 3 2 4 6% 33%	3480
	21st to end	Night	19% 11% 3 7% 4 4 3 3 4 5% 38%	3817
April	1st to 10th	Night	18% 12% 3 7% 5% 5% 4 3 5% 7% 34%	2007
	11th to 20th	Night	17% 9% 3 7% 5% 4 4 3 5% 7% 37%	1832
	21st to end	Night	16% 10% 3 7% 4 3 4 3 7% 7% 37%	1710
May	1st to 10th	Night	18% 9% 3 7% 5% 5% 5% 4 6% 7% 31%	1710
	11th to 20th	Night	17% 7% 3 7% 4 4 4 4 5% 7% 38%	1628
	21st to end	Night	9% 5% 2 5% 4 4 5% 4 8% 10% 43%	1642
June	1st to 10th	Night	10% 6% 2 7% 5% 4 4 4 5% 9% 44%	1440
	11th to 20th	Night	12% 6% 2 6% 5% 5% 4 4 6% 10% 41%	1440
	21st to end	Night	10% 4 2 4 5% 5% 6% 4 6% 9% 45%	1440
July	1st to 10th	Night	8% 6% 2 5% 4 5% 5% 4 7% 8% 45%	1556
	11th to 20th	Night	8% 5% 2 6% 3 4 5% 4 7% 10% 47%	1620
	21st to end	Night	11% 5% 2 7% 5% 5% 6% 5% 7% 8% 40%	1771
August	1st to 10th	Night	8% 5% 2 5% 4 5% 5% 5% 8% 9% 43%	1611
	11th to 20th	Night	10% 6% 2 7% 4 4 4 5% 6% 8% 45%	1598
	21st to end	Night	11% 6% 2 5% 3 4 5% 5% 6% 9% 45%	1864
September	1st to 10th	Night	14% 4 2 5% 3 4 3 4 5% 6% 50%	1819
	11th to 20th	Night	10% 5% 2 4 3 3 4 4 5% 9% 52%	1980
	21st to end	Night	16% 6% 2 6% 4 4 4 4 5% 6% 43%	1980
October	1st to 10th	Night	15% 6% 2 6% 4 4 4 4 5% 7% 45%	2144
	11th to 20th	Night	18% 7% 2 7% 5% 4 5% 4 5% 5% 38%	2160
	21st to end	Night	25% 8% 3 6% 3 3 3 3 4 6% 35%	2376
November	1st to 10th	Night	14% 8% 3 5% 5% 4 3 3 5% 6% 45%	2317
	11th to 20th	Night	19% 12% 3 6% 4 4 4 4 5% 6% 33%	2556
	21st to end	Night	19% 13% 4 8% 4 5% 4 4 4 6% 29%	2660
December	1st to 10th	Night	23% 17% 7% 9% 4 3 4 3 4 6% 20%	2660
	11th to 20th	Night	19% 18% 6% 11% 4 3 3 3 5% 5% 24%	3285
	21st to end	Night	25% 20% 6% 9% 5% 4 4 3 4 5% 14%	4820

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	68% 6% 10% 12% 5%	2837
	11th to 20th	Day	72% 4 7% 12% 4 1	2840
	21st to end	Day	77% 4 7% 9% 2	3124
February	1st to 10th	Day	65% 5% 9% 14% 7% 1	1710
	11th to 20th	Day	63% 5% 8% 16% 8%	1672
	21st to end	Day	61% 4 11% 16% 8% 2	1579
March	1st to 10th	Day	57% 6% 9% 22% 6%	3435
	11th to 20th	Day	51% 5% 10% 24% 8% 1	3480
	21st to end	Day	52% 5% 9% 20% 12% 1	3815
April	1st to 10th	Day	52% 7% 10% 19% 11% 2	2171
	11th to 20th	Day	50% 6% 9% 17% 15% 2	2313
	21st to end	Day	51% 6% 9% 22% 10% 2	2470
May	1st to 10th	Day	53% 7% 11% 18% 10% 1	2470
	11th to 20th	Day	53% 7% 11% 16% 11% 2	2357
	21st to end	Day	40% 10% 16% 23% 10% 2	2629
June	1st to 10th	Day	44% 8% 14% 21% 12% 1	2520
	11th to 20th	Day	44% 8% 13% 22% 12% 1	2520
	21st to end	Day	41% 8% 12% 24% 13% 1	2520
July	1st to 10th	Day	41% 9% 13% 21% 14% 3	2332
	11th to 20th	Day	41% 8% 12% 23% 15% 1	2271
	21st to end	Day	42% 9% 12% 23% 12% 2	2405
August	1st to 10th	Day	42% 8% 14% 26% 9%	2314
	11th to 20th	Day	42% 9% 15% 24% 10% 1	2303
	21st to end	Day	41% 8% 12% 22% 13% 4	2472
September	1st to 10th	Day	40% 7% 10% 22% 18% 3	2138
	11th to 20th	Day	36% 6% 14% 27% 14% 2	1980
	21st to end	Day	47% 5% 9% 23% 15%	1980
October	1st to 10th	Day	42% 6% 12% 21% 17% 1	1815
	11th to 20th	Day	50% 5% 11% 22% 11%	1800
	21st to end	Day	54% 5% 11% 19% 11% 1	1980
November	1st to 10th	Day	42% 5% 12% 22% 16% 2	1758
	11th to 20th	Day	54% 4 9% 20% 10% 2	1620
	21st to end	Day	57% 7% 11% 16% 8% 1	1520
December	1st to 10th	Day	69% 6% 9% 12% 4	1520
	11th to 20th	Day	66% 4 10% 17% 4	1906
	21st to end	Day	74% 5% 9% 9% 3	2832
January	1st to 10th	Night	69% 4 9% 14% 4	4109
	11th to 20th	Night	72% 5% 9% 10% 3	4120
	21st to end	Night	75% 3 6% 12% 3	4532
February	1st to 10th	Night	62% 5% 8% 17% 7%	2470
	11th to 20th	Night	62% 4 9% 17% 7%	2405
	21st to end	Night	63% 4 8% 15% 9% 1	1872
March	1st to 10th	Night	54% 4 9% 23% 9%	3418
	11th to 20th	Night	51% 5% 11% 25% 7% 1	3480
	21st to end	Night	48% 5% 9% 23% 12% 2	3817
April	1st to 10th	Night	50% 6% 10% 19% 13% 2	2007
	11th to 20th	Night	47% 6% 11% 17% 16% 3	1832
	21st to end	Night	45% 5% 11% 22% 13% 3	1710
May	1st to 10th	Night	50% 7% 8% 19% 12% 3	1710
	11th to 20th	Night	45% 8% 11% 18% 15% 2	1629
	21st to end	Night	34% 9% 16% 26% 14% 1	1643
June	1st to 10th	Night	37% 9% 12% 25% 16% 2	1440
	11th to 20th	Night	39% 7% 14% 24% 15% 2	1440
	21st to end	Night	35% 9% 12% 25% 17% 2	1440
July	1st to 10th	Night	36% 9% 12% 22% 17% 4	1511
	11th to 20th	Night	30% 10% 15% 25% 18% 2	1566
	21st to end	Night	38% 10% 14% 22% 13% 3	1672
August	1st to 10th	Night	33% 10% 15% 27% 16%	1600
	11th to 20th	Night	36% 8% 13% 25% 15% 2	1598
	21st to end	Night	34% 8% 13% 26% 16% 4	1864
September	1st to 10th	Night	34% 6% 11% 24% 20% 5%	1819
	11th to 20th	Night	30% 6% 13% 27% 23% 1	1980
	21st to end	Night	42% 5% 11% 22% 19% 1	1980
October	1st to 10th	Night	39% 7% 12% 24% 16% 2	2144
	11th to 20th	Night	46% 5% 10% 24% 14% 1	2160
	21st to end	Night	51% 5% 10% 20% 12% 2	2376
November	1st to 10th	Night	40% 4 11% 24% 17% 4	2317
	11th to 20th	Night	52% 4 10% 20% 11% 2	2556
	21st to end	Night	56% 4 11% 21% 7% 1	2660
December	1st to 10th	Night	66% 4 10% 14% 5%	2660
	11th to 20th	Night	64% 4 11% 17% 4	3288
	21st to end	Night	72% 6% 9% 10% 3	4820

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	34% 25% 25% 11% 4	270
	11th to 20th	Day	37% 27% 26% 7% 1	270
	21st to end	Day	31% 32% 28% 6% 3	297
February	1st to 10th	Day	36% 21% 34% 8% 1	270
	11th to 20th	Day	37% 31% 26% 5% 1	270
	21st to end	Day	40% 27% 26% 7%	235
March	1st to 10th	Day	30% 20% 30% 16% 3	460
	11th to 20th	Day	32% 21% 30% 12% 5% 1	460
	21st to end	Day	32% 22% 27% 15% 4	506
April	1st to 10th	Day	32% 19% 26% 15% 7% 2	460
	11th to 20th	Day	26% 20% 27% 16% 8% 3	452
	21st to end	Day	30% 17% 32% 14% 6% 2	460
May	1st to 10th	Day	28% 21% 25% 17% 6% 3	463
	11th to 20th	Day	22% 15% 33% 18% 8% 4	463
	21st to end	Day	17% 9% 27% 23% 17% 7%	485
June	1st to 10th	Day	14% 9% 32% 28% 15% 2	450
	11th to 20th	Day	19% 12% 24% 27% 14% 4	450
	21st to end	Day	12% 12% 32% 26% 15% 3	450
July	1st to 10th	Day	14% 6% 20% 27% 22% 11%	445
	11th to 20th	Day	12% 5% 29% 28% 18% 8%	444
	21st to end	Day	12% 8% 24% 30% 18% 8%	488
August	1st to 10th	Day	12% 7% 22% 31% 20% 9%	446
	11th to 20th	Day	15% 7% 21% 28% 18% 10%	439
	21st to end	Day	12% 5% 24% 27% 21% 11%	495
September	1st to 10th	Day	18% 7% 20% 27% 21% 7%	450
	11th to 20th	Day	13% 5% 19% 30% 22% 11%	450
	21st to end	Day	21% 11% 26% 23% 15% 5%	450
October	1st to 10th	Day	17% 9% 29% 24% 15% 5%	450
	11th to 20th	Day	24% 18% 28% 22% 8%	450
	21st to end	Day	31% 16% 30% 18% 5%	495
November	1st to 10th	Day	22% 15% 34% 16% 10% 3	356
	11th to 20th	Day	34% 17% 26% 16% 6% 1	228
	21st to end	Day	27% 22% 39% 11% 1	180
December	1st to 10th	Day	31% 27% 27% 10% 3 2	180
	11th to 20th	Day	31% 23% 34% 11% 2	180
	21st to end	Day	36% 24% 27% 11% 3	214
January	1st to 10th	Night	30% 19% 33% 15% 2	760
	11th to 20th	Night	32% 18% 31% 16% 3	760
	21st to end	Night	28% 21% 29% 19% 3	836
February	1st to 10th	Night	32% 16% 29% 21% 3	760
	11th to 20th	Night	29% 22% 33% 14% 1	743
	21st to end	Night	28% 20% 31% 18% 2	628
March	1st to 10th	Night	26% 18% 31% 22% 3	760
	11th to 20th	Night	27% 18% 27% 22% 5% 1	760
	21st to end	Night	27% 16% 32% 20% 5%	836
April	1st to 10th	Night	25% 16% 30% 23% 6%	760
	11th to 20th	Night	23% 14% 31% 22% 9% 1	708
	21st to end	Night	20% 11% 35% 29% 6%	570
May	1st to 10th	Night	23% 9% 26% 32% 9% 2	570
	11th to 20th	Night	20% 8% 28% 29% 13% 1	543
	21st to end	Night	12% 2 24% 35% 24% 3	482
June	1st to 10th	Night	11% 5% 24% 43% 18%	360
	11th to 20th	Night	14% 5% 23% 38% 19% 1	360
	21st to end	Night	10% 4 27% 36% 23% 1	360
July	1st to 10th	Night	8% 3 17% 40% 25% 7%	461
	11th to 20th	Night	8% 2 21% 37% 27% 4	522
	21st to end	Night	12% 3 14% 40% 27% 3	591
August	1st to 10th	Night	10% 1 16% 40% 29% 3	537
	11th to 20th	Night	11% 3 12% 39% 30% 4	534
	21st to end	Night	12% 4 20% 30% 30% 5%	676
September	1st to 10th	Night	15% 3 18% 32% 27% 5%	720
	11th to 20th	Night	12% 4 16% 35% 29% 4	720
	21st to end	Night	18% 7% 23% 26% 22% 4	720
October	1st to 10th	Night	17% 9% 23% 29% 21% 2	720
	11th to 20th	Night	22% 12% 30% 25% 11% 1	720
	21st to end	Night	29% 13% 27% 25% 7%	792
November	1st to 10th	Night	18% 12% 28% 29% 13%	740
	11th to 20th	Night	29% 13% 28% 23% 7% 1	760
	21st to end	Night	29% 14% 30% 21% 6%	760
December	1st to 10th	Night	33% 19% 26% 18% 4	760
	11th to 20th	Night	28% 19% 29% 20% 3	760
	21st to end	Night	31% 17% 30% 19% 2	836

Page generated at 2024-05-12 00:20:39. Version ac07

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