Cooper Lake State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cooper Lake State Park clear sky chart from 2005-11-06 to 2024-01-27.

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	12% 5% 2 4 4 3 4 4 5% 7% 49%	75082
	Night	11% 4 2 4 4 2 3 4 5% 7% 54%	74991
Transparency	Day	35% 6% 10% 23% 21% 6%	74807
	Night	30% 5% 10% 22% 23% 10%	74786
Seeing	Day	13% 6% 21% 27% 25% 8%	14103
	Night	13% 6% 26% 34% 19% 2	24109

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	14% 7% 2 4 2 2 3 2 4 6% 54%	1707
	11th to 20th	Day	16% 5% 2 3 3 2 3 4 4 4 54%	1710
	21st to end	Day	18% 7% 3 4 3 2 2 3 3 5% 50%	1836
February	1st to 10th	Day	21% 7% 3 5% 4 2 4 3 3 5% 42%	1624
	11th to 20th	Day	20% 6% 3 5% 4 2 3 4 4 5% 43%	1749
	21st to end	Day	23% 7% 2 4 3 2 2 2 3 5% 46%	1570
March	1st to 10th	Day	18% 6% 2 4 4 2 4 4 4 5% 46%	1980
	11th to 20th	Day	20% 5% 2 5% 4 2 3 3 4 6% 45%	1980
	21st to end	Day	14% 6% 3 6% 5% 3 4 4 5% 5% 44%	2178
April	1st to 10th	Day	13% 7% 2 5% 5% 3 4 3 4 6% 46%	1980
	11th to 20th	Day	16% 4 2 5% 4 3 4 4 6% 6% 45%	2121
	21st to end	Day	13% 5% 3 5% 5% 2 4 4 6% 8% 45%	2191
May	1st to 10th	Day	14% 5% 3 5% 5% 2 4 5% 4 6% 46%	2340
	11th to 20th	Day	12% 5% 3 6% 5% 3 5% 5% 6% 7% 43%	2302
	21st to end	Day	11% 7% 4 6% 6% 3 6% 6% 6% 8% 38%	2531
June	1st to 10th	Day	7% 3 2 4 6% 3 5% 6% 7% 9% 48%	2340
	11th to 20th	Day	5% 4 3 4 5% 4 6% 5% 6% 9% 48%	2340
	21st to end	Day	5% 3 2 4 4 3 5% 5% 7% 9% 54%	2340
July	1st to 10th	Day	7% 4 3 6% 7% 3 8% 6% 7% 11% 38%	2340
	11th to 20th	Day	4 2 1 3 4 3 5% 6% 6% 10% 55%	2340
	21st to end	Day	5% 3 2 4 5% 4 6% 6% 7% 11% 49%	2546
August	1st to 10th	Day	3 2 1 3 4 3 5% 5% 6% 10% 58%	2328
	11th to 20th	Day	8% 4 2 4 5% 3 5% 5% 6% 9% 48%	2301
	21st to end	Day	6% 4 2 5% 5% 4 5% 5% 7% 11% 47%	2381
September	1st to 10th	Day	10% 4 2 4 5% 3 5% 4 5% 6% 52%	1994
	11th to 20th	Day	11% 4 2 5% 5% 4 5% 5% 6% 7% 47%	1980
	21st to end	Day	8% 3 1 3 4 3 4 4 5% 8% 57%	1980
October	1st to 10th	Day	6% 4 2 4 5% 2 4 4 4 6% 59%	1865
	11th to 20th	Day	14% 3 2 4 3 2 3 3 3 5% 59%	1800
	21st to end	Day	16% 5% 2 4 3 2 3 2 4 4 55%	1980
November	1st to 10th	Day	11% 5% 2 5% 3 2 4 4 4 6% 54%	1858
	11th to 20th	Day	10% 3 2 4 5% 3 3 4 4 6% 57%	1854
	21st to end	Day	17% 6% 2 4 3 2 2 3 3 6% 52%	1710
December	1st to 10th	Day	16% 6% 2 4 3 3 4 4 4 5% 48%	1710
	11th to 20th	Day	16% 8% 3 5% 5% 3 3 4 4 5% 45%	2161
	21st to end	Day	18% 9% 3 4 3 2 3 3 4 6% 45%	3135
January	1st to 10th	Night	14% 6% 2 3 3 2 3 3 4 5% 55%	2458
	11th to 20th	Night	17% 5% 1 3 3 2 3 2 5% 6% 53%	2470
	21st to end	Night	16% 6% 2 3 4 2 3 3 3 4 53%	2665
February	1st to 10th	Night	17% 6% 2 4 3 2 3 4 4 5% 51%	2340
	11th to 20th	Night	17% 7% 3 5% 4 2 3 3 4 5% 48%	2107
	21st to end	Night	20% 5% 2 4 2 2 3 3 4 4 50%	1686
March	1st to 10th	Night	16% 5% 2 5% 4 2 3 4 4 7% 48%	1980
	11th to 20th	Night	16% 6% 3 5% 4 3 3 4 4 7% 46%	1980
	21st to end	Night	13% 5% 3 4 4 2 4 4 5% 6% 51%	2178
April	1st to 10th	Night	12% 4 2 4 4 2 4 4 5% 8% 52%	1980
	11th to 20th	Night	14% 5% 2 3 4 2 4 4 5% 7% 50%	1785
	21st to end	Night	12% 5% 2 4 3 1 3 3 4 8% 54%	1765
May	1st to 10th	Night	10% 4 3 4 4 2 4 4 5% 10% 51%	1620
	11th to 20th	Night	11% 4 1 4 5% 2 4 4 7% 9% 50%	1593
	21st to end	Night	7% 5% 2 4 5% 3 5% 5% 6% 10% 48%	1745
June	1st to 10th	Night	4 3 2 4 5% 2 4 5% 5% 10% 57%	1620
	11th to 20th	Night	4 3 1 3 2 3 2 3 6% 9% 64%	1620
	21st to end	Night	4 2 1 2 3 3 3 4 6% 9% 61%	1620
July	1st to 10th	Night	4 3 2 4 4 3 4 5% 8% 12% 51%	1620
	11th to 20th	Night	3 1 1 2 2 2 3 4 5% 11% 66%	1620
	21st to end	Night	2 2 1 3 4 3 4 5% 6% 11% 58%	1772
August	1st to 10th	Night	2 1 1 3 2 2 3 4 6% 11% 65%	1611
	11th to 20th	Night	6% 3 1 4 3 3 4 4 6% 9% 56%	1600
	21st to end	Night	4 3 2 4 5% 3 6% 6% 7% 9% 52%	1973
September	1st to 10th	Night	6% 4 2 4 4 2 4 4 5% 8% 58%	1962
	11th to 20th	Night	10% 4 1 5% 4 3 3 5% 5% 6% 53%	1980
	21st to end	Night	7% 2 2 3 3 2 3 4 5% 6% 64%	1980
October	1st to 10th	Night	7% 2 1 3 3 2 2 3 5% 7% 64%	2075
	11th to 20th	Night	13% 4 1 3 2 1 3 3 3 5% 62%	2160
	21st to end	Night	17% 5% 1 3 2 2 2 2 3 5% 59%	2376
November	1st to 10th	Night	10% 4 2 4 4 2 3 3 4 4 59%	2220
	11th to 20th	Night	9% 4 2 4 3 2 5% 4 4 6% 58%	2322
	21st to end	Night	15% 5% 2 4 4 2 3 4 4 6% 51%	2470
December	1st to 10th	Night	15% 6% 2 4 3 2 3 3 4 6% 52%	2470
	11th to 20th	Night	14% 6% 3 4 5% 3 3 3 4 6% 47%	3036
	21st to end	Night	17% 6% 2 4 4 2 3 3 4 6% 50%	4532

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	34% 3 8% 21% 27% 6%	1708
	11th to 20th	Day	36% 4 7% 23% 26% 5%	1710
	21st to end	Day	39% 3 5% 19% 27% 8%	1836
February	1st to 10th	Day	47% 4 5% 18% 18% 8%	1624
	11th to 20th	Day	46% 3 6% 21% 17% 7%	1759
	21st to end	Day	44% 2 5% 15% 25% 9%	1570
March	1st to 10th	Day	41% 4 7% 17% 20% 11%	1980
	11th to 20th	Day	42% 4 9% 20% 20% 5%	1980
	21st to end	Day	42% 5% 8% 20% 20% 5%	2178
April	1st to 10th	Day	40% 4 9% 22% 18% 8%	1980
	11th to 20th	Day	39% 6% 9% 18% 21% 7%	2121
	21st to end	Day	37% 6% 8% 22% 23% 4	2191
May	1st to 10th	Day	39% 6% 8% 24% 18% 6%	2340
	11th to 20th	Day	38% 8% 13% 23% 17% 1	2306
	21st to end	Day	43% 8% 12% 21% 15% 2	2531
June	1st to 10th	Day	31% 8% 14% 29% 16% 2	2340
	11th to 20th	Day	31% 7% 16% 26% 17% 3	2340
	21st to end	Day	25% 7% 12% 31% 22% 3	2340
July	1st to 10th	Day	38% 10% 17% 25% 10%	2276
	11th to 20th	Day	21% 8% 15% 33% 21% 2	2271
	21st to end	Day	26% 8% 19% 33% 13%	2405
August	1st to 10th	Day	19% 8% 17% 35% 20% 2	2314
	11th to 20th	Day	31% 7% 14% 27% 18% 3	2301
	21st to end	Day	30% 8% 16% 28% 15% 3	2381
September	1st to 10th	Day	33% 6% 9% 21% 21% 10%	1994
	11th to 20th	Day	35% 7% 12% 19% 20% 7%	1980
	21st to end	Day	26% 5% 10% 21% 27% 11%	1980
October	1st to 10th	Day	27% 5% 11% 20% 21% 15%	1865
	11th to 20th	Day	32% 3 5% 17% 29% 15%	1800
	21st to end	Day	34% 3 7% 17% 26% 13%	1980
November	1st to 10th	Day	32% 4 8% 23% 24% 9%	1858
	11th to 20th	Day	29% 4 8% 21% 28% 9%	1854
	21st to end	Day	37% 3 6% 19% 27% 9%	1710
December	1st to 10th	Day	38% 5% 7% 22% 22% 7%	1710
	11th to 20th	Day	42% 3 5% 17% 25% 8%	2159
	21st to end	Day	41% 4 5% 21% 22% 7%	3135
January	1st to 10th	Night	33% 3 7% 19% 28% 10%	2458
	11th to 20th	Night	34% 3 9% 19% 26% 9%	2470
	21st to end	Night	37% 3 5% 15% 28% 12%	2665
February	1st to 10th	Night	37% 4 7% 21% 21% 10%	2340
	11th to 20th	Night	41% 3 6% 19% 23% 8%	2107
	21st to end	Night	40% 4 7% 14% 21% 14%	1686
March	1st to 10th	Night	38% 5% 8% 18% 18% 13%	1980
	11th to 20th	Night	40% 5% 8% 15% 23% 9%	1980
	21st to end	Night	34% 5% 10% 20% 25% 6%	2178
April	1st to 10th	Night	31% 6% 11% 22% 19% 12%	1980
	11th to 20th	Night	33% 5% 9% 21% 19% 12%	1785
	21st to end	Night	30% 4 11% 24% 26% 5%	1765
May	1st to 10th	Night	32% 6% 11% 23% 19% 9%	1620
	11th to 20th	Night	31% 6% 17% 26% 18% 3	1594
	21st to end	Night	30% 7% 16% 26% 17% 3	1746
June	1st to 10th	Night	23% 7% 16% 30% 20% 4	1620
	11th to 20th	Night	19% 5% 14% 36% 21% 6%	1620
	21st to end	Night	19% 7% 12% 29% 27% 5%	1620
July	1st to 10th	Night	25% 8% 17% 32% 17% 1	1575
	11th to 20th	Night	13% 7% 14% 35% 26% 5%	1566
	21st to end	Night	17% 8% 18% 37% 19% 1	1673
August	1st to 10th	Night	13% 6% 16% 35% 25% 4	1601
	11th to 20th	Night	26% 6% 11% 29% 21% 6%	1600
	21st to end	Night	26% 7% 14% 31% 19% 3	1973
September	1st to 10th	Night	26% 5% 10% 23% 26% 9%	1962
	11th to 20th	Night	31% 5% 11% 22% 22% 11%	1980
	21st to end	Night	22% 4 9% 21% 29% 15%	1980
October	1st to 10th	Night	21% 4 11% 25% 21% 18%	2075
	11th to 20th	Night	26% 2 8% 15% 27% 21%	2160
	21st to end	Night	31% 2 5% 19% 25% 17%	2376
November	1st to 10th	Night	28% 4 8% 19% 27% 14%	2220
	11th to 20th	Night	28% 4 7% 20% 26% 14%	2322
	21st to end	Night	36% 4 7% 17% 27% 9%	2470
December	1st to 10th	Night	35% 4 9% 20% 22% 10%	2470
	11th to 20th	Night	40% 3 5% 16% 24% 12%	3037
	21st to end	Night	36% 4 7% 19% 26% 9%	4532

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	20% 14% 33% 27% 6%	270
	11th to 20th	Day	20% 19% 34% 20% 7% 1	270
	21st to end	Day	21% 15% 35% 20% 9% 1	282
February	1st to 10th	Day	29% 11% 33% 20% 6%	240
	11th to 20th	Day	28% 15% 37% 18% 3	240
	21st to end	Day	33% 15% 38% 11% 3	198
March	1st to 10th	Day	22% 16% 33% 23% 6%	240
	11th to 20th	Day	23% 18% 33% 18% 5% 1	240
	21st to end	Day	16% 18% 39% 22% 6%	264
April	1st to 10th	Day	18% 16% 33% 26% 7% 1	240
	11th to 20th	Day	22% 13% 32% 24% 10%	399
	21st to end	Day	16% 12% 38% 24% 8% 2	451
May	1st to 10th	Day	14% 10% 31% 34% 10% 1	603
	11th to 20th	Day	14% 6% 27% 33% 16% 4	625
	21st to end	Day	13% 4 25% 34% 19% 5%	679
June	1st to 10th	Day	7% 2 11% 35% 34% 11%	630
	11th to 20th	Day	6% 2 15% 40% 29% 8%	630
	21st to end	Day	5% 1 12% 33% 37% 13%	630
July	1st to 10th	Day	6% 1 10% 29% 38% 15%	621
	11th to 20th	Day	3 6% 29% 47% 15%	618
	21st to end	Day	3 4 25% 50% 16%	684
August	1st to 10th	Day	4 5% 29% 48% 14%	626
	11th to 20th	Day	9% 6% 28% 44% 12%	615
	21st to end	Day	7% 1 5% 21% 40% 27%	500
September	1st to 10th	Day	7% 1 2 21% 42% 28%	284
	11th to 20th	Day	3 1 9% 24% 39% 24%	270
	21st to end	Day	11% 3 9% 26% 33% 19%	270
October	1st to 10th	Day	4 2 20% 28% 36% 10%	270
	11th to 20th	Day	11% 7% 26% 31% 19% 6%	270
	21st to end	Day	26% 8% 25% 22% 18% 3	297
November	1st to 10th	Day	16% 6% 31% 28% 16% 4	270
	11th to 20th	Day	14% 7% 32% 32% 11% 3	270
	21st to end	Day	22% 13% 29% 24% 10% 2	270
December	1st to 10th	Day	22% 10% 31% 25% 11% 1	270
	11th to 20th	Day	19% 13% 39% 21% 7%	270
	21st to end	Day	21% 12% 39% 21% 5% 1	297
January	1st to 10th	Night	16% 10% 33% 32% 8%	950
	11th to 20th	Night	20% 13% 32% 29% 6% 1	950
	21st to end	Night	18% 9% 37% 30% 6%	1025
February	1st to 10th	Night	21% 10% 35% 28% 6%	900
	11th to 20th	Night	22% 10% 37% 29% 3	713
	21st to end	Night	24% 15% 34% 25% 3	502
March	1st to 10th	Night	18% 12% 33% 29% 7%	540
	11th to 20th	Night	16% 11% 35% 31% 6%	540
	21st to end	Night	14% 11% 35% 34% 6% 1	594
April	1st to 10th	Night	12% 10% 44% 27% 7%	540
	11th to 20th	Night	16% 11% 36% 26% 11%	533
	21st to end	Night	12% 8% 39% 31% 9% 1	540
May	1st to 10th	Night	11% 4 38% 36% 9% 1	540
	11th to 20th	Night	11% 4 27% 37% 18% 2	531
	21st to end	Night	8% 3 23% 42% 21% 3	584
June	1st to 10th	Night	5% 2 12% 43% 36% 2	540
	11th to 20th	Night	6% 2 18% 48% 25% 1	540
	21st to end	Night	4 2 10% 39% 39% 6%	540
July	1st to 10th	Night	3 1 9% 40% 42% 6%	525
	11th to 20th	Night	3 5% 37% 49% 5%	522
	21st to end	Night	2 1 6% 37% 47% 7%	591
August	1st to 10th	Night	2 5% 37% 51% 5%	537
	11th to 20th	Night	7% 6% 33% 48% 6%	534
	21st to end	Night	4 1 4 35% 48% 8%	594
September	1st to 10th	Night	7% 1 7% 33% 45% 7%	540
	11th to 20th	Night	12% 1 7% 33% 43% 4	540
	21st to end	Night	7% 1 11% 41% 36% 5%	540
October	1st to 10th	Night	9% 1 16% 42% 28% 3	635
	11th to 20th	Night	15% 3 24% 38% 18% 2	720
	21st to end	Night	17% 7% 28% 30% 16% 2	792
November	1st to 10th	Night	11% 4 27% 41% 16% 1	740
	11th to 20th	Night	10% 8% 28% 40% 11% 1	802
	21st to end	Night	17% 9% 32% 30% 11%	950
December	1st to 10th	Night	18% 7% 32% 36% 7%	950
	11th to 20th	Night	22% 8% 31% 33% 6%	950
	21st to end	Night	19% 9% 34% 31% 7%	1045

Page generated at 2024-01-24 08:37:31. Version ac07

Copyright 2024 Attilla Danko