Burr Oak State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Burr Oak State Park clear sky chart from 2005-11-06 to 2024-12-09.

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	15% 10% 3 7% 5% 4 5% 4 5% 7% 34%	101526
	Night	16% 10% 3 7% 5% 4 4 3 5% 6% 36%	98215
Transparency	Day	47% 5% 11% 22% 13% 2	105241
	Night	47% 5% 10% 22% 14% 2	102638
Seeing	Day	22% 13% 28% 21% 12% 5%	15058
	Night	21% 11% 25% 27% 14% 2	25161

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% 20% 5% 9% 4 3 4 3 5% 6% 21%	2836
	11th to 20th	Day	14% 21% 9% 12% 6% 5% 3 2 3 4 20%	2840
	21st to end	Day	26% 21% 7% 8% 5% 4 3 3 3 4 16%	3124
February	1st to 10th	Day	22% 14% 4 8% 5% 3 3 3 4 5% 27%	1710
	11th to 20th	Day	18% 14% 5% 11% 4 3 3 4 5% 6% 27%	1783
	21st to end	Day	20% 14% 5% 8% 4 4 3 2 4 5% 32%	1570
March	1st to 10th	Day	23% 16% 4 8% 4 4 4 2 4 6% 26%	3341
	11th to 20th	Day	14% 8% 3 7% 5% 4 5% 4 5% 6% 39%	3480
	21st to end	Day	20% 8% 3 8% 4 4 5% 4 5% 6% 34%	3815
April	1st to 10th	Day	15% 13% 3 7% 6% 5% 4 3 5% 6% 33%	2090
	11th to 20th	Day	16% 9% 3 7% 5% 4 4 3 5% 6% 38%	2403
	21st to end	Day	18% 8% 3 7% 4 4 5% 4 5% 7% 35%	2470
May	1st to 10th	Day	21% 10% 3 8% 5% 5% 4 4 5% 6% 28%	4082
	11th to 20th	Day	21% 10% 3 7% 4 4 4 3 6% 7% 32%	4081
	21st to end	Day	11% 6% 2 6% 5% 6% 5% 5% 8% 10% 36%	4476
June	1st to 10th	Day	13% 6% 2 5% 6% 5% 5% 5% 7% 9% 37%	2470
	11th to 20th	Day	10% 6% 2 7% 6% 6% 5% 5% 7% 9% 36%	2470
	21st to end	Day	11% 6% 3 6% 5% 5% 6% 5% 7% 10% 36%	2470
July	1st to 10th	Day	10% 6% 2 7% 5% 5% 5% 5% 6% 9% 40%	4120
	11th to 20th	Day	9% 5% 2 5% 4 4 5% 4 7% 11% 43%	4120
	21st to end	Day	14% 7% 3 7% 6% 5% 6% 4 6% 9% 33%	4466
August	1st to 10th	Day	9% 6% 2 8% 5% 5% 6% 5% 7% 10% 36%	4104
	11th to 20th	Day	9% 6% 2 7% 5% 5% 6% 5% 7% 10% 39%	4044
	21st to end	Day	6% 3 2 6% 4 5% 6% 4 6% 9% 50%	4450
September	1st to 10th	Day	15% 5% 2 5% 4 4 4 3 5% 6% 48%	2109
	11th to 20th	Day	9% 6% 2 5% 4 4 5% 4 5% 8% 48%	2090
	21st to end	Day	19% 7% 3 6% 4 4 3 3 5% 6% 41%	2090
October	1st to 10th	Day	13% 6% 2 6% 4 4 4 3 6% 7% 45%	1997
	11th to 20th	Day	15% 7% 2 7% 5% 4 4 3 5% 7% 42%	1900
	21st to end	Day	21% 8% 3 7% 4 4 4 2 4 6% 38%	2090
November	1st to 10th	Day	12% 7% 2 6% 4 3 3 3 4 6% 50%	1776
	11th to 20th	Day	17% 14% 4 7% 4 4 3 3 5% 6% 35%	1800
	21st to end	Day	17% 13% 4 8% 4 3 5% 3 4 6% 32%	1800
December	1st to 10th	Day	22% 15% 5% 10% 5% 5% 4 3 4 4 23%	1782
	11th to 20th	Day	18% 16% 5% 11% 5% 4 4 3 5% 6% 24%	2153
	21st to end	Day	21% 22% 5% 10% 5% 5% 5% 4 4 5% 15%	3124
January	1st to 10th	Night	16% 19% 6% 11% 6% 5% 4 4 4 4 20%	4109
	11th to 20th	Night	18% 17% 6% 14% 5% 4 5% 3 4 5% 18%	4120
	21st to end	Night	27% 17% 6% 10% 6% 3 3 2 3 4 19%	4532
February	1st to 10th	Night	22% 12% 4 8% 5% 4 4 3 4 5% 29%	2470
	11th to 20th	Night	20% 14% 4 9% 5% 5% 4 3 5% 5% 27%	2279
	21st to end	Night	21% 15% 6% 8% 5% 4 4 3 4 4 28%	1884
March	1st to 10th	Night	21% 13% 3 6% 4 4 3 3 4 6% 33%	3510
	11th to 20th	Night	14% 9% 3 6% 4 4 5% 4 5% 6% 39%	3480
	21st to end	Night	19% 9% 2 6% 3 3 4 4 4 6% 40%	3817
April	1st to 10th	Night	16% 10% 2 6% 4 4 4 4 6% 7% 37%	2090
	11th to 20th	Night	15% 8% 2 5% 5% 4 4 3 6% 8% 39%	1741
	21st to end	Night	15% 8% 2 7% 5% 4 4 3 7% 7% 37%	1710
May	1st to 10th	Night	26% 11% 3 7% 4 4 4 3 4 7% 27%	2813
	11th to 20th	Night	20% 8% 3 6% 4 3 3 3 3 6% 41%	2812
	21st to end	Night	11% 6% 2 6% 4 4 4 4 7% 10% 43%	3079
June	1st to 10th	Night	10% 5% 2 5% 4 4 5% 5% 7% 9% 44%	1710
	11th to 20th	Night	9% 5% 2 7% 4 4 4 5% 8% 9% 44%	1710
	21st to end	Night	10% 5% 2 5% 4 4 5% 4 6% 10% 45%	1710
July	1st to 10th	Night	10% 7% 3 6% 4 4 4 4 6% 8% 45%	2840
	11th to 20th	Night	9% 5% 2 6% 5% 4 5% 5% 7% 8% 45%	2840
	21st to end	Night	9% 7% 3 8% 6% 5% 5% 5% 6% 7% 39%	3087
August	1st to 10th	Night	8% 7% 3 8% 4 5% 5% 4 7% 9% 39%	2825
	11th to 20th	Night	11% 7% 3 8% 4 5% 5% 3 5% 7% 44%	2785
	21st to end	Night	6% 3 2 7% 4 4 5% 4 7% 10% 49%	3173
September	1st to 10th	Night	11% 5% 2 6% 3 4 4 3 4 7% 52%	2066
	11th to 20th	Night	9% 4 2 5% 4 3 5% 4 5% 7% 53%	2090
	21st to end	Night	16% 8% 2 5% 4 3 5% 3 5% 5% 44%	2090
October	1st to 10th	Night	12% 5% 2 6% 4 3 4 3 5% 7% 50%	2181
	11th to 20th	Night	15% 7% 2 5% 4 3 4 4 5% 7% 44%	2280
	21st to end	Night	20% 7% 2 5% 3 3 4 3 5% 5% 42%	2508
November	1st to 10th	Night	14% 7% 2 4 4 3 3 3 4 6% 50%	2519
	11th to 20th	Night	17% 10% 3 6% 5% 5% 4 3 5% 6% 35%	2600
	21st to end	Night	18% 12% 4 7% 4 5% 4 3 5% 6% 32%	2600
December	1st to 10th	Night	21% 15% 5% 9% 5% 5% 4 3 4 5% 25%	2581
	11th to 20th	Night	18% 15% 6% 7% 5% 4 4 3 5% 6% 27%	3042
	21st to end	Night	20% 19% 6% 10% 5% 4 4 3 4 5% 18%	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	65% 4 12% 13% 6%	2837
	11th to 20th	Day	69% 3 8% 14% 5%	2840
	21st to end	Day	74% 2 8% 12% 4 1	3124
February	1st to 10th	Day	60% 3 11% 17% 9% 1	1710
	11th to 20th	Day	59% 3 10% 17% 10%	1792
	21st to end	Day	57% 3 10% 19% 9% 1	1570
March	1st to 10th	Day	60% 4 9% 20% 7% 1	3341
	11th to 20th	Day	45% 5% 9% 28% 13% 1	3480
	21st to end	Day	50% 5% 9% 23% 13%	3815
April	1st to 10th	Day	52% 4 9% 20% 12% 3	2090
	11th to 20th	Day	46% 5% 11% 18% 16% 4	2403
	21st to end	Day	49% 5% 10% 22% 12% 2	2470
May	1st to 10th	Day	55% 6% 9% 21% 8% 1	4120
	11th to 20th	Day	51% 6% 9% 18% 15% 1	4085
	21st to end	Day	39% 9% 14% 20% 14% 4	4489
June	1st to 10th	Day	40% 8% 13% 23% 15% 2	2470
	11th to 20th	Day	41% 8% 13% 22% 15% 1	2470
	21st to end	Day	40% 8% 14% 22% 14% 2	2470
July	1st to 10th	Day	40% 6% 12% 23% 16% 2	4055
	11th to 20th	Day	34% 7% 11% 33% 14% 1	4051
	21st to end	Day	46% 7% 10% 18% 16% 3	4324
August	1st to 10th	Day	40% 7% 14% 27% 11% 1	4091
	11th to 20th	Day	37% 7% 11% 31% 14% 1	4083
	21st to end	Day	29% 7% 14% 31% 16% 3	4450
September	1st to 10th	Day	36% 6% 10% 22% 22% 5%	2109
	11th to 20th	Day	33% 5% 12% 26% 21% 2	2090
	21st to end	Day	45% 4 9% 23% 18% 1	2090
October	1st to 10th	Day	25% 4 9% 31% 28% 2	3322
	11th to 20th	Day	34% 4 12% 27% 19% 4	3140
	21st to end	Day	35% 3 12% 28% 20% 2	3428
November	1st to 10th	Day	36% 4 9% 30% 18% 3	1776
	11th to 20th	Day	51% 4 8% 21% 14% 2	1800
	21st to end	Day	54% 3 10% 20% 12% 1	1800
December	1st to 10th	Day	65% 4 10% 17% 4	1782
	11th to 20th	Day	62% 3 10% 18% 7%	2150
	21st to end	Day	71% 4 11% 10% 4	3124
January	1st to 10th	Night	68% 3 9% 15% 5%	4109
	11th to 20th	Night	69% 3 11% 14% 3	4120
	21st to end	Night	72% 2 7% 15% 3 1	4532
February	1st to 10th	Night	58% 4 10% 18% 9% 1	2470
	11th to 20th	Night	59% 4 9% 18% 10% 1	2280
	21st to end	Night	60% 3 9% 17% 8% 2	1884
March	1st to 10th	Night	54% 4 6% 23% 12% 1	3510
	11th to 20th	Night	44% 5% 10% 29% 12% 1	3480
	21st to end	Night	46% 4 8% 28% 13% 2	3817
April	1st to 10th	Night	46% 5% 11% 20% 15% 3	2090
	11th to 20th	Night	43% 4 11% 20% 18% 5%	1741
	21st to end	Night	44% 5% 11% 22% 15% 2	1710
May	1st to 10th	Night	57% 5% 9% 17% 9% 2	2840
	11th to 20th	Night	46% 6% 9% 25% 13% 2	2813
	21st to end	Night	34% 7% 14% 27% 13% 4	3087
June	1st to 10th	Night	35% 8% 11% 25% 19% 3	1710
	11th to 20th	Night	34% 8% 15% 24% 18% 2	1710
	21st to end	Night	34% 6% 15% 24% 18% 3	1710
July	1st to 10th	Night	37% 6% 10% 24% 18% 5%	2795
	11th to 20th	Night	35% 7% 12% 29% 16% 2	2786
	21st to end	Night	41% 8% 11% 20% 15% 4	2988
August	1st to 10th	Night	39% 7% 14% 27% 11% 1	2814
	11th to 20th	Night	39% 6% 10% 22% 22% 1	2812
	21st to end	Night	28% 7% 13% 30% 18% 3	3173
September	1st to 10th	Night	32% 6% 12% 22% 22% 7%	2066
	11th to 20th	Night	30% 6% 11% 24% 26% 3	2090
	21st to end	Night	41% 5% 9% 22% 22% 2	2090
October	1st to 10th	Night	28% 4 7% 28% 29% 3	3636
	11th to 20th	Night	31% 4 11% 25% 22% 7%	3779
	21st to end	Night	32% 3 8% 27% 26% 4	4120
November	1st to 10th	Night	37% 3 11% 25% 19% 4	2519
	11th to 20th	Night	49% 3 9% 20% 15% 3	2600
	21st to end	Night	54% 3 12% 20% 10% 1	2600
December	1st to 10th	Night	62% 5% 10% 18% 5% 1	2581
	11th to 20th	Night	58% 4 11% 20% 7%	3044
	21st to end	Night	69% 3 10% 14% 4	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	29% 23% 33% 11% 3 1	270
	11th to 20th	Day	34% 26% 33% 6% 1	270
	21st to end	Day	35% 23% 30% 9% 3	297
February	1st to 10th	Day	39% 22% 26% 11% 3	270
	11th to 20th	Day	38% 26% 31% 3 2	270
	21st to end	Day	36% 21% 36% 7%	225
March	1st to 10th	Day	30% 21% 28% 18% 4	400
	11th to 20th	Day	30% 21% 31% 13% 5%	460
	21st to end	Day	31% 18% 33% 14% 4	506
April	1st to 10th	Day	26% 20% 29% 16% 8% 1	460
	11th to 20th	Day	29% 16% 29% 16% 7% 3	452
	21st to end	Day	25% 18% 32% 17% 6% 1	460
May	1st to 10th	Day	27% 19% 27% 16% 7% 3	463
	11th to 20th	Day	23% 13% 30% 20% 10% 5%	487
	21st to end	Day	12% 9% 29% 28% 15% 7%	529
June	1st to 10th	Day	15% 9% 27% 28% 15% 6%	490
	11th to 20th	Day	15% 10% 24% 31% 12% 7%	490
	21st to end	Day	13% 9% 30% 28% 15% 6%	490
July	1st to 10th	Day	14% 5% 20% 26% 20% 16%	485
	11th to 20th	Day	9% 6% 25% 29% 21% 10%	484
	21st to end	Day	15% 4 23% 26% 22% 10%	532
August	1st to 10th	Day	12% 6% 20% 30% 22% 11%	486
	11th to 20th	Day	14% 5% 20% 32% 18% 11%	479
	21st to end	Day	9% 5% 21% 30% 23% 12%	539
September	1st to 10th	Day	15% 5% 19% 27% 22% 12%	490
	11th to 20th	Day	11% 3 17% 27% 29% 13%	490
	21st to end	Day	22% 11% 24% 23% 17% 4	490
October	1st to 10th	Day	13% 9% 29% 25% 18% 6%	490
	11th to 20th	Day	19% 12% 31% 22% 12% 3	490
	21st to end	Day	26% 14% 32% 18% 9%	539
November	1st to 10th	Day	18% 16% 33% 24% 7% 2	314
	11th to 20th	Day	29% 17% 31% 15% 6% 2	300
	21st to end	Day	29% 20% 33% 15% 3	300
December	1st to 10th	Day	29% 20% 35% 10% 5% 1	294
	11th to 20th	Day	26% 24% 37% 9% 3 1	270
	21st to end	Day	35% 21% 27% 13% 5%	297
January	1st to 10th	Night	29% 18% 32% 18% 3	760
	11th to 20th	Night	32% 19% 27% 19% 3	760
	21st to end	Night	28% 18% 31% 21% 2	836
February	1st to 10th	Night	29% 15% 29% 25% 1	760
	11th to 20th	Night	31% 19% 32% 17% 1	743
	21st to end	Night	31% 17% 32% 18% 2	628
March	1st to 10th	Night	27% 14% 30% 24% 5%	760
	11th to 20th	Night	26% 19% 26% 21% 7% 1	760
	21st to end	Night	26% 15% 30% 22% 6%	836
April	1st to 10th	Night	23% 16% 33% 22% 7%	760
	11th to 20th	Night	19% 14% 32% 25% 9% 1	611
	21st to end	Night	19% 12% 35% 28% 6% 1	570
May	1st to 10th	Night	19% 11% 29% 28% 12% 2	570
	11th to 20th	Night	20% 9% 24% 31% 15% 1	561
	21st to end	Night	12% 4 22% 33% 26% 3	617
June	1st to 10th	Night	10% 5% 23% 39% 22% 1	570
	11th to 20th	Night	11% 4 20% 37% 27% 2	570
	21st to end	Night	13% 4 22% 36% 24% 2	570
July	1st to 10th	Night	12% 3 15% 35% 29% 6%	555
	11th to 20th	Night	7% 3 17% 36% 32% 5%	552
	21st to end	Night	11% 3 16% 33% 34% 2	624
August	1st to 10th	Night	8% 3 13% 38% 34% 4	567
	11th to 20th	Night	9% 2 16% 38% 29% 5%	564
	21st to end	Night	10% 2 15% 30% 36% 6%	650
September	1st to 10th	Night	13% 3 16% 34% 27% 7%	760
	11th to 20th	Night	11% 3 13% 35% 32% 5%	760
	21st to end	Night	19% 6% 21% 30% 21% 3	760
October	1st to 10th	Night	13% 6% 21% 33% 24% 3	760
	11th to 20th	Night	20% 10% 26% 28% 15% 1	760
	21st to end	Night	24% 11% 27% 28% 10% 1	836
November	1st to 10th	Night	20% 10% 27% 28% 15% 1	780
	11th to 20th	Night	24% 15% 27% 26% 8% 1	800
	21st to end	Night	27% 13% 26% 29% 6% 1	800
December	1st to 10th	Night	31% 14% 30% 19% 6%	795
	11th to 20th	Night	27% 17% 27% 23% 6%	760
	21st to end	Night	31% 15% 28% 24% 2	836

Page generated at 2024-12-06 03:54:51. Version ac07

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