Battle Creek
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Battle Creek 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	14% 10% 4 9% 5% 5% 5% 4 5% 7% 32%	119759
	Night	15% 12% 4 10% 5% 4 4 3 5% 6% 31%	119504
Transparency	Day	50% 6% 11% 20% 12% 1	123359
	Night	52% 5% 11% 19% 12% 1	124045
Seeing	Day	19% 16% 30% 21% 11% 4	16720
	Night	20% 12% 30% 26% 10% 1	26565

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	12% 17% 8% 19% 7% 5% 4 3 4 4 17%	3617
	11th to 20th	Day	13% 14% 7% 20% 11% 11% 8% 3 3 3 8%	3620
	21st to end	Day	20% 18% 8% 16% 6% 4 5% 3 3 4 14%	4053
February	1st to 10th	Day	15% 15% 6% 13% 10% 6% 4 3 5% 4 19%	1855
	11th to 20th	Day	14% 14% 6% 15% 8% 5% 4 3 4 5% 22%	1948
	21st to end	Day	15% 18% 5% 12% 5% 5% 4 4 6% 5% 22%	1650
March	1st to 10th	Day	14% 13% 5% 12% 6% 5% 4 3 4 5% 29%	4480
	11th to 20th	Day	11% 10% 4 8% 6% 5% 5% 4 6% 7% 35%	4888
	21st to end	Day	19% 15% 5% 9% 5% 4 5% 3 5% 5% 24%	5589
April	1st to 10th	Day	19% 15% 3 7% 5% 5% 4 4 5% 6% 29%	2400
	11th to 20th	Day	17% 12% 3 6% 4 4 5% 3 5% 6% 36%	2445
	21st to end	Day	17% 9% 3 7% 5% 4 5% 3 6% 7% 35%	2600
May	1st to 10th	Day	21% 9% 2 6% 5% 4 4 3 6% 7% 33%	5862
	11th to 20th	Day	14% 7% 3 7% 5% 4 4 4 6% 8% 37%	5861
	21st to end	Day	16% 7% 2 7% 4 4 4 4 6% 8% 41%	6753
June	1st to 10th	Day	10% 5% 2 7% 5% 4 4 5% 6% 8% 42%	2800
	11th to 20th	Day	11% 5% 2 6% 5% 4 5% 5% 6% 8% 43%	2800
	21st to end	Day	10% 6% 3 6% 5% 5% 6% 5% 7% 9% 38%	2800
July	1st to 10th	Day	11% 6% 2 7% 5% 5% 5% 5% 7% 10% 37%	4580
	11th to 20th	Day	8% 4 2 4 4 4 6% 3 7% 10% 48%	4580
	21st to end	Day	7% 5% 2 7% 5% 5% 6% 4 7% 9% 43%	4757
August	1st to 10th	Day	12% 5% 2 5% 4 4 5% 5% 6% 9% 42%	4104
	11th to 20th	Day	11% 5% 2 6% 4 5% 4 4 6% 7% 45%	4044
	21st to end	Day	8% 5% 2 7% 5% 5% 5% 5% 6% 8% 45%	4257
September	1st to 10th	Day	11% 6% 2 6% 5% 5% 5% 4 5% 7% 43%	2223
	11th to 20th	Day	11% 4 2 5% 3 3 5% 4 6% 9% 48%	2090
	21st to end	Day	13% 7% 3 7% 5% 4 4 3 5% 8% 40%	2090
October	1st to 10th	Day	14% 8% 3 6% 5% 4 3 4 5% 7% 42%	2090
	11th to 20th	Day	19% 9% 3 8% 5% 5% 5% 3 5% 8% 30%	1878
	21st to end	Day	21% 12% 3 8% 5% 5% 5% 4 5% 7% 27%	1881
November	1st to 10th	Day	12% 13% 3 7% 3 3 5% 4 5% 7% 38%	1762
	11th to 20th	Day	15% 16% 5% 10% 6% 5% 5% 3 4 7% 24%	1800
	21st to end	Day	20% 16% 7% 9% 5% 4 4 3 5% 6% 23%	1800
December	1st to 10th	Day	10% 19% 10% 15% 7% 4 5% 3 4 6% 16%	2812
	11th to 20th	Day	18% 21% 11% 12% 8% 4 3 3 3 4 14%	3008
	21st to end	Day	24% 23% 7% 12% 5% 4 3 2 3 5% 11%	3982
January	1st to 10th	Night	13% 17% 8% 21% 6% 4 4 3 4 4 16%	6348
	11th to 20th	Night	13% 17% 8% 21% 9% 7% 6% 4 3 3 9%	6360
	21st to end	Night	19% 16% 7% 14% 6% 6% 5% 3 4 4 16%	6907
February	1st to 10th	Night	14% 17% 5% 12% 9% 5% 4 4 4 4 21%	2540
	11th to 20th	Night	14% 14% 5% 12% 8% 5% 5% 3 4 5% 25%	2338
	21st to end	Night	18% 10% 5% 11% 6% 4 4 4 5% 7% 26%	1980
March	1st to 10th	Night	15% 11% 4 8% 4 4 4 3 4 7% 35%	5373
	11th to 20th	Night	11% 8% 3 7% 4 3 4 3 5% 7% 44%	5057
	21st to end	Night	17% 13% 4 9% 4 4 3 2 5% 5% 33%	5384
April	1st to 10th	Night	16% 12% 3 6% 5% 4 3 3 5% 7% 36%	2000
	11th to 20th	Night	18% 9% 3 6% 4 4 4 3 5% 6% 37%	1903
	21st to end	Night	17% 9% 3 7% 4 4 4 3 5% 7% 38%	1800
May	1st to 10th	Night	19% 11% 3 7% 5% 4 4 3 4 7% 31%	4033
	11th to 20th	Night	18% 7% 3 6% 4 4 3 3 4 6% 42%	4032
	21st to end	Night	16% 7% 2 6% 4 3 3 3 5% 7% 43%	4099
June	1st to 10th	Night	11% 5% 2 5% 4 4 3 4 5% 10% 47%	1600
	11th to 20th	Night	11% 6% 2 5% 5% 4 4 4 7% 10% 43%	1600
	21st to end	Night	9% 4 2 6% 5% 4 5% 4 7% 9% 46%	1600
July	1st to 10th	Night	9% 5% 2 6% 4 4 5% 4 7% 11% 44%	2610
	11th to 20th	Night	8% 3 1 4 4 3 4 3 5% 7% 57%	2610
	21st to end	Night	7% 5% 3 6% 4 4 5% 5% 6% 9% 47%	2804
August	1st to 10th	Night	11% 5% 2 6% 4 4 4 3 6% 9% 48%	2825
	11th to 20th	Night	11% 6% 2 6% 3 4 4 4 6% 9% 44%	2785
	21st to end	Night	10% 6% 2 7% 5% 4 4 4 5% 7% 46%	3396
September	1st to 10th	Night	9% 7% 2 5% 4 3 4 4 6% 7% 49%	1937
	11th to 20th	Night	10% 5% 2 5% 3 3 4 3 4 7% 54%	2090
	21st to end	Night	15% 7% 2 6% 4 4 4 4 5% 6% 43%	2090
October	1st to 10th	Night	15% 7% 2 5% 4 3 3 3 4 6% 47%	2090
	11th to 20th	Night	18% 11% 3 8% 5% 4 4 3 4 6% 35%	2298
	21st to end	Night	21% 11% 3 7% 4 4 4 3 5% 6% 32%	2717
November	1st to 10th	Night	14% 11% 4 7% 5% 4 4 3 5% 5% 40%	2536
	11th to 20th	Night	15% 16% 4 9% 6% 5% 4 4 6% 7% 26%	2600
	21st to end	Night	18% 16% 6% 8% 5% 4 4 3 4 6% 25%	2600
December	1st to 10th	Night	12% 16% 10% 16% 6% 5% 4 3 4 5% 18%	4367
	11th to 20th	Night	17% 22% 9% 15% 7% 4 3 3 3 4 13%	5199
	21st to end	Night	26% 22% 6% 11% 4 4 4 3 4 4 13%	6996

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	71% 5% 9% 13% 2	3618
	11th to 20th	Day	84% 3 6% 4 2	3620
	21st to end	Day	76% 3 9% 9% 3	4053
February	1st to 10th	Day	68% 5% 9% 12% 5%	1855
	11th to 20th	Day	66% 4 8% 14% 8% 1	1958
	21st to end	Day	63% 6% 11% 12% 6% 1	1650
March	1st to 10th	Day	57% 5% 11% 18% 8%	4480
	11th to 20th	Day	46% 5% 16% 22% 9% 1	4888
	21st to end	Day	62% 5% 8% 14% 10% 1	5591
April	1st to 10th	Day	56% 5% 9% 19% 11%	2400
	11th to 20th	Day	48% 6% 10% 21% 13% 2	2445
	21st to end	Day	48% 6% 12% 18% 15% 2	2600
May	1st to 10th	Day	50% 6% 10% 18% 15% 1	5897
	11th to 20th	Day	43% 7% 14% 22% 12% 1	5865
	21st to end	Day	41% 6% 10% 23% 19% 2	6767
June	1st to 10th	Day	37% 7% 11% 26% 16% 2	2800
	11th to 20th	Day	36% 8% 12% 24% 18% 2	2800
	21st to end	Day	40% 8% 12% 21% 16% 2	2800
July	1st to 10th	Day	42% 6% 13% 21% 16% 3	4511
	11th to 20th	Day	29% 7% 14% 31% 18% 1	4505
	21st to end	Day	35% 8% 15% 19% 22% 2	4607
August	1st to 10th	Day	37% 8% 13% 25% 16% 1	4091
	11th to 20th	Day	36% 7% 12% 30% 14% 1	4083
	21st to end	Day	35% 7% 12% 30% 14% 2	4256
September	1st to 10th	Day	39% 7% 13% 22% 16% 2	2223
	11th to 20th	Day	32% 6% 13% 29% 19% 1	2090
	21st to end	Day	42% 6% 12% 23% 17%	2090
October	1st to 10th	Day	30% 4 8% 38% 18% 1	3480
	11th to 20th	Day	41% 4 11% 25% 18%	3094
	21st to end	Day	49% 4 11% 24% 11% 2	3081
November	1st to 10th	Day	46% 5% 14% 22% 13% 1	1762
	11th to 20th	Day	62% 5% 9% 17% 6% 1	1800
	21st to end	Day	64% 5% 13% 14% 5%	1800
December	1st to 10th	Day	69% 6% 12% 9% 2	2812
	11th to 20th	Day	75% 4 9% 10% 2	3005
	21st to end	Day	78% 4 6% 9% 3	3982
January	1st to 10th	Night	71% 4 8% 12% 4 1	6348
	11th to 20th	Night	81% 4 7% 5% 3	6360
	21st to end	Night	72% 4 12% 9% 3	6907
February	1st to 10th	Night	65% 5% 10% 12% 6% 1	2540
	11th to 20th	Night	61% 5% 9% 16% 7%	2339
	21st to end	Night	58% 5% 13% 16% 7% 2	1980
March	1st to 10th	Night	49% 5% 13% 24% 9% 1	5373
	11th to 20th	Night	39% 5% 13% 27% 15% 1	5057
	21st to end	Night	53% 4 10% 18% 13% 1	5384
April	1st to 10th	Night	48% 6% 10% 21% 13% 1	2000
	11th to 20th	Night	48% 4 10% 19% 17% 2	1903
	21st to end	Night	45% 7% 10% 20% 15% 2	1800
May	1st to 10th	Night	52% 7% 8% 17% 14% 2	4060
	11th to 20th	Night	43% 6% 10% 24% 15% 2	4033
	21st to end	Night	40% 6% 10% 22% 20% 2	4107
June	1st to 10th	Night	32% 7% 11% 30% 18% 2	1600
	11th to 20th	Night	36% 8% 14% 24% 17% 2	1600
	21st to end	Night	34% 7% 17% 24% 17% 2	1600
July	1st to 10th	Night	34% 6% 13% 26% 15% 6%	2570
	11th to 20th	Night	26% 7% 12% 30% 23% 2	2562
	21st to end	Night	33% 7% 16% 17% 25% 3	2715
August	1st to 10th	Night	33% 6% 12% 33% 14% 1	2814
	11th to 20th	Night	34% 6% 12% 30% 16% 1	2812
	21st to end	Night	36% 6% 10% 29% 16% 2	3396
September	1st to 10th	Night	33% 8% 9% 27% 20% 3	1937
	11th to 20th	Night	31% 5% 9% 32% 22% 1	2090
	21st to end	Night	41% 6% 10% 26% 16% 1	2090
October	1st to 10th	Night	28% 3 9% 35% 24% 1	3480
	11th to 20th	Night	43% 4 11% 21% 21%	3821
	21st to end	Night	41% 4 9% 29% 16% 1	4467
November	1st to 10th	Night	47% 5% 10% 23% 14% 1	2536
	11th to 20th	Night	57% 5% 13% 16% 8% 1	2600
	21st to end	Night	61% 5% 12% 17% 5%	2600
December	1st to 10th	Night	68% 5% 12% 11% 4	4367
	11th to 20th	Night	76% 5% 8% 9% 3	5201
	21st to end	Night	76% 4 8% 8% 4	6996

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	21% 25% 37% 14% 3	300
	11th to 20th	Day	23% 28% 39% 7% 3	300
	21st to end	Day	27% 26% 32% 13% 2	330
February	1st to 10th	Day	28% 25% 32% 12% 1 1	300
	11th to 20th	Day	30% 25% 32% 12% 1	300
	21st to end	Day	30% 31% 31% 7% 1	249
March	1st to 10th	Day	23% 28% 37% 10% 2	300
	11th to 20th	Day	24% 20% 34% 17% 5%	460
	21st to end	Day	31% 19% 32% 14% 4 1	550
April	1st to 10th	Day	26% 21% 33% 16% 4 1	500
	11th to 20th	Day	29% 22% 28% 12% 7% 3	492
	21st to end	Day	25% 20% 29% 19% 6% 1	500
May	1st to 10th	Day	25% 16% 30% 20% 7% 2	503
	11th to 20th	Day	20% 13% 31% 20% 11% 5%	527
	21st to end	Day	14% 15% 28% 25% 14% 4	711
June	1st to 10th	Day	12% 13% 32% 30% 9% 4	730
	11th to 20th	Day	14% 10% 34% 28% 12% 3	730
	21st to end	Day	13% 13% 33% 28% 10% 3	730
July	1st to 10th	Day	8% 7% 26% 31% 19% 9%	721
	11th to 20th	Day	12% 7% 29% 27% 17% 7%	718
	21st to end	Day	9% 6% 28% 30% 20% 7%	707
August	1st to 10th	Day	9% 5% 26% 26% 22% 13%	486
	11th to 20th	Day	11% 7% 22% 32% 21% 7%	479
	21st to end	Day	10% 6% 25% 29% 22% 8%	539
September	1st to 10th	Day	16% 9% 23% 23% 22% 8%	490
	11th to 20th	Day	9% 6% 20% 31% 27% 8%	490
	21st to end	Day	17% 14% 22% 26% 14% 7%	490
October	1st to 10th	Day	17% 11% 28% 25% 13% 5%	490
	11th to 20th	Day	23% 18% 31% 23% 5%	438
	21st to end	Day	28% 23% 36% 11% 3	330
November	1st to 10th	Day	23% 19% 34% 19% 5% 1	300
	11th to 20th	Day	27% 26% 31% 12% 4	300
	21st to end	Day	29% 22% 38% 11% 1	300
December	1st to 10th	Day	26% 32% 27% 10% 4 1	300
	11th to 20th	Day	23% 31% 32% 12% 2	300
	21st to end	Day	27% 28% 32% 9% 2	330
January	1st to 10th	Night	22% 20% 33% 20% 4	1000
	11th to 20th	Night	25% 18% 33% 19% 4 1	1000
	21st to end	Night	22% 16% 36% 23% 3	1063
February	1st to 10th	Night	24% 19% 35% 20% 3	800
	11th to 20th	Night	21% 19% 35% 22% 3	783
	21st to end	Night	24% 20% 38% 16% 3	660
March	1st to 10th	Night	22% 17% 33% 22% 5% 1	800
	11th to 20th	Night	18% 16% 38% 22% 5%	800
	21st to end	Night	24% 15% 33% 22% 6%	848
April	1st to 10th	Night	19% 16% 37% 24% 5% 1	600
	11th to 20th	Night	23% 16% 33% 23% 5% 1	593
	21st to end	Night	22% 11% 35% 26% 5% 1	600
May	1st to 10th	Night	22% 9% 32% 29% 7% 1	600
	11th to 20th	Night	22% 9% 29% 29% 10% 1	591
	21st to end	Night	14% 6% 30% 33% 16% 2	650
June	1st to 10th	Night	12% 6% 29% 39% 14% 1	600
	11th to 20th	Night	14% 3 28% 40% 14%	600
	21st to end	Night	10% 4 27% 39% 19% 2	600
July	1st to 10th	Night	9% 3 21% 38% 26% 4	585
	11th to 20th	Night	9% 2 23% 41% 21% 4	582
	21st to end	Night	7% 2 21% 43% 26% 1	624
August	1st to 10th	Night	10% 2 17% 42% 27% 3	567
	11th to 20th	Night	9% 2 18% 41% 25% 4	564
	21st to end	Night	11% 3 20% 34% 29% 4	627
September	1st to 10th	Night	12% 5% 22% 34% 22% 5%	607
	11th to 20th	Night	12% 5% 19% 35% 26% 3	760
	21st to end	Night	19% 7% 23% 30% 17% 4	760
October	1st to 10th	Night	18% 9% 27% 28% 17% 1	760
	11th to 20th	Night	23% 14% 29% 25% 8% 1	760
	21st to end	Night	27% 16% 31% 21% 6%	836
November	1st to 10th	Night	21% 14% 28% 27% 8% 1	780
	11th to 20th	Night	24% 17% 35% 19% 5% 1	800
	21st to end	Night	26% 17% 34% 20% 4	800
December	1st to 10th	Night	26% 20% 33% 16% 5%	865
	11th to 20th	Night	26% 17% 38% 17% 3	1000
	21st to end	Night	32% 17% 34% 15% 2	1100

Page generated at 2025-07-18 01:10:01. Version ac07

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