IU Kokomo Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the IU Kokomo Observatory 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	14% 9% 4 8% 5% 4 4 4 5% 7% 36%	126641
	Night	15% 10% 4 8% 5% 4 4 3 5% 6% 36%	124205
Transparency	Day	46% 5% 11% 23% 13% 1	130222
	Night	47% 4 10% 22% 14% 2	128697
Seeing	Day	18% 10% 27% 24% 15% 6%	17102
	Night	18% 10% 29% 29% 13% 1	26912

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% 15% 9% 16% 6% 4 4 3 5% 5% 21%	3617
	11th to 20th	Day	13% 14% 9% 13% 7% 8% 7% 5% 4 4 17%	3620
	21st to end	Day	23% 18% 7% 11% 4 3 3 3 3 4 21%	4087
February	1st to 10th	Day	17% 14% 7% 11% 7% 5% 4 3 4 5% 24%	1975
	11th to 20th	Day	16% 13% 4 10% 7% 5% 4 3 4 6% 29%	1948
	21st to end	Day	16% 14% 6% 9% 4 3 4 5% 4 5% 30%	1650
March	1st to 10th	Day	19% 15% 6% 9% 4 4 3 2 3 4 31%	4480
	11th to 20th	Day	11% 11% 3 5% 4 4 4 3 6% 7% 42%	4811
	21st to end	Day	17% 13% 5% 9% 5% 5% 5% 3 5% 7% 28%	5709
April	1st to 10th	Day	17% 11% 4 8% 5% 4 5% 4 5% 6% 32%	2400
	11th to 20th	Day	17% 10% 3 6% 5% 4 4 3 6% 6% 36%	2374
	21st to end	Day	18% 9% 3 7% 4 5% 3 3 5% 7% 35%	2586
May	1st to 10th	Day	19% 9% 3 7% 5% 5% 5% 4 6% 8% 28%	5862
	11th to 20th	Day	18% 7% 3 7% 5% 4 5% 4 5% 7% 36%	5861
	21st to end	Day	14% 6% 2 7% 4 5% 5% 4 6% 10% 37%	6680
June	1st to 10th	Day	11% 6% 2 7% 6% 5% 4 4 6% 7% 42%	2800
	11th to 20th	Day	10% 5% 2 5% 4 5% 6% 4 7% 8% 44%	2800
	21st to end	Day	10% 5% 2 6% 6% 4 5% 5% 6% 9% 42%	2800
July	1st to 10th	Day	11% 5% 2 6% 4 4 5% 4 7% 10% 41%	6360
	11th to 20th	Day	8% 5% 2 6% 5% 5% 6% 4 7% 11% 40%	6360
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 7% 8% 39%	6797
August	1st to 10th	Day	8% 5% 2 6% 4 4 5% 4 7% 9% 47%	4234
	11th to 20th	Day	10% 5% 2 6% 4 5% 4 5% 6% 10% 44%	4028
	21st to end	Day	7% 4 2 6% 4 4 4 4 5% 9% 51%	4312
September	1st to 10th	Day	10% 6% 2 6% 4 4 5% 3 6% 7% 48%	2370
	11th to 20th	Day	10% 4 2 5% 4 4 5% 4 5% 8% 50%	2200
	21st to end	Day	13% 6% 3 5% 4 4 5% 3 6% 7% 45%	2200
October	1st to 10th	Day	12% 6% 3 5% 4 5% 4 3 5% 7% 47%	2200
	11th to 20th	Day	15% 7% 3 6% 4 4 4 4 5% 6% 42%	2019
	21st to end	Day	18% 9% 3 8% 5% 4 4 4 5% 7% 33%	1980
November	1st to 10th	Day	11% 8% 2 5% 4 4 4 3 5% 6% 49%	1852
	11th to 20th	Day	17% 13% 4 7% 4 5% 4 2 5% 6% 34%	1890
	21st to end	Day	19% 12% 3 9% 5% 4 4 3 4 4 32%	1890
December	1st to 10th	Day	12% 13% 4 9% 5% 3 3 3 4 5% 40%	2899
	11th to 20th	Day	16% 15% 7% 11% 6% 5% 5% 3 5% 5% 23%	3008
	21st to end	Day	28% 18% 7% 11% 5% 4 4 3 4 4 11%	3982
January	1st to 10th	Night	16% 15% 9% 14% 6% 4 4 3 4 4 23%	6348
	11th to 20th	Night	12% 20% 8% 15% 7% 6% 5% 3 4 3 18%	6360
	21st to end	Night	20% 14% 5% 10% 5% 5% 4 3 3 4 27%	6883
February	1st to 10th	Night	19% 15% 5% 10% 5% 4 3 3 4 4 28%	2421
	11th to 20th	Night	14% 12% 5% 11% 6% 5% 3 3 5% 5% 32%	2338
	21st to end	Night	19% 13% 4 10% 4 3 3 3 4 6% 32%	1980
March	1st to 10th	Night	18% 12% 4 6% 4 3 4 2 4 5% 37%	5373
	11th to 20th	Night	13% 7% 2 5% 4 5% 4 4 5% 7% 43%	5148
	21st to end	Night	19% 9% 3 7% 5% 4 4 4 5% 6% 34%	5248
April	1st to 10th	Night	14% 9% 3 7% 5% 4 4 4 5% 6% 39%	2000
	11th to 20th	Night	17% 9% 3 6% 5% 4 4 3 5% 7% 38%	1975
	21st to end	Night	17% 8% 3 6% 4 4 5% 4 5% 7% 36%	1812
May	1st to 10th	Night	21% 10% 3 8% 5% 5% 4 3 5% 7% 29%	4033
	11th to 20th	Night	16% 7% 3 6% 4 4 4 4 6% 9% 40%	4032
	21st to end	Night	14% 7% 3 6% 4 4 5% 4 5% 7% 40%	4169
June	1st to 10th	Night	9% 5% 2 7% 4 3 5% 4 5% 6% 50%	1600
	11th to 20th	Night	9% 5% 2 6% 4 5% 4 5% 6% 9% 46%	1600
	21st to end	Night	9% 7% 1 5% 4 5% 5% 5% 5% 9% 45%	1600
July	1st to 10th	Night	9% 4 2 6% 5% 4 4 4 6% 10% 46%	3618
	11th to 20th	Night	8% 5% 2 6% 4 4 4 4 7% 10% 48%	3617
	21st to end	Night	11% 6% 3 7% 5% 4 4 4 5% 8% 41%	4067
August	1st to 10th	Night	11% 4 2 5% 3 4 4 3 6% 8% 50%	2915
	11th to 20th	Night	8% 5% 2 6% 4 4 5% 4 7% 7% 48%	3004
	21st to end	Night	8% 4 1 6% 4 3 3 3 5% 8% 53%	3586
September	1st to 10th	Night	12% 5% 2 6% 4 4 3 3 4 7% 51%	2009
	11th to 20th	Night	8% 5% 2 5% 3 3 3 3 4 7% 59%	2200
	21st to end	Night	12% 7% 2 5% 3 4 3 3 5% 6% 49%	2200
October	1st to 10th	Night	10% 5% 2 5% 3 4 3 3 5% 6% 54%	2200
	11th to 20th	Night	16% 6% 2 6% 3 4 3 3 5% 7% 44%	2378
	21st to end	Night	17% 8% 3 7% 4 4 4 3 4 7% 38%	2860
November	1st to 10th	Night	12% 8% 3 5% 4 3 3 4 5% 6% 47%	2666
	11th to 20th	Night	15% 10% 3 7% 4 3 4 3 5% 7% 39%	2730
	21st to end	Night	19% 14% 4 8% 6% 3 4 3 4 6% 30%	2730
December	1st to 10th	Night	13% 11% 3 7% 5% 4 4 3 5% 6% 39%	4310
	11th to 20th	Night	17% 15% 7% 10% 5% 4 4 3 4 5% 25%	5199
	21st to end	Night	25% 19% 6% 10% 5% 4 4 3 4 4 14%	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	66% 2 7% 19% 5%	3618
	11th to 20th	Day	71% 3 9% 8% 7% 2	3620
	21st to end	Day	69% 2 9% 12% 7% 1	4087
February	1st to 10th	Day	65% 3 9% 14% 8% 1	1975
	11th to 20th	Day	57% 3 10% 21% 8% 1	1958
	21st to end	Day	56% 4 11% 19% 8% 2	1650
March	1st to 10th	Day	59% 2 6% 20% 11% 1	4480
	11th to 20th	Day	41% 3 10% 35% 10% 1	4811
	21st to end	Day	57% 4 14% 18% 6% 2	5711
April	1st to 10th	Day	51% 5% 12% 19% 12% 1	2400
	11th to 20th	Day	48% 4 10% 24% 10% 3	2374
	21st to end	Day	49% 4 12% 23% 10% 3	2586
May	1st to 10th	Day	54% 5% 12% 18% 11%	5897
	11th to 20th	Day	48% 4 12% 23% 12% 1	5865
	21st to end	Day	42% 5% 12% 26% 14% 1	6694
June	1st to 10th	Day	40% 5% 11% 26% 16% 3	2800
	11th to 20th	Day	36% 5% 11% 25% 19% 3	2800
	21st to end	Day	38% 7% 16% 20% 16% 3	2800
July	1st to 10th	Day	36% 6% 11% 27% 17% 2	6291
	11th to 20th	Day	35% 9% 16% 26% 14% 1	6285
	21st to end	Day	40% 8% 13% 21% 16% 2	6602
August	1st to 10th	Day	31% 8% 18% 28% 15% 1	4221
	11th to 20th	Day	33% 7% 13% 31% 15% 1	4067
	21st to end	Day	29% 6% 14% 29% 19% 3	4311
September	1st to 10th	Day	35% 5% 13% 25% 18% 4	2370
	11th to 20th	Day	32% 5% 9% 28% 24% 3	2200
	21st to end	Day	37% 5% 11% 24% 22% 2	2200
October	1st to 10th	Day	26% 3 10% 32% 27% 2	3590
	11th to 20th	Day	34% 5% 10% 24% 26% 1	3261
	21st to end	Day	43% 4 9% 26% 18% 1	3180
November	1st to 10th	Day	37% 3 13% 28% 17% 2	1852
	11th to 20th	Day	52% 2 10% 21% 12% 2	1890
	21st to end	Day	56% 3 10% 21% 8% 1	1890
December	1st to 10th	Day	48% 2 13% 27% 10%	2899
	11th to 20th	Day	64% 3 11% 18% 4	3005
	21st to end	Day	77% 4 8% 8% 3	3982
January	1st to 10th	Night	66% 3 8% 16% 7%	6348
	11th to 20th	Night	72% 2 6% 10% 8% 2	6360
	21st to end	Night	63% 3 10% 16% 8% 1	6883
February	1st to 10th	Night	60% 3 12% 15% 8% 1	2421
	11th to 20th	Night	55% 3 9% 19% 12% 1	2339
	21st to end	Night	55% 3 10% 19% 10% 2	1980
March	1st to 10th	Night	51% 3 7% 27% 10% 2	5373
	11th to 20th	Night	40% 4 12% 28% 15% 2	5148
	21st to end	Night	50% 4 11% 26% 8% 1	5248
April	1st to 10th	Night	46% 4 12% 23% 14% 2	2000
	11th to 20th	Night	46% 3 10% 22% 15% 4	1975
	21st to end	Night	46% 5% 9% 23% 13% 3	1812
May	1st to 10th	Night	56% 4 9% 17% 12% 3	4060
	11th to 20th	Night	42% 5% 13% 25% 14% 1	4033
	21st to end	Night	42% 6% 11% 23% 14% 2	4177
June	1st to 10th	Night	34% 5% 10% 27% 21% 3	1600
	11th to 20th	Night	34% 6% 12% 24% 22% 3	1600
	21st to end	Night	35% 5% 16% 23% 16% 4	1600
July	1st to 10th	Night	33% 6% 12% 28% 16% 5%	3580
	11th to 20th	Night	31% 7% 16% 26% 19% 1	3572
	21st to end	Night	39% 8% 14% 21% 15% 3	3950
August	1st to 10th	Night	32% 6% 15% 30% 15% 1	2904
	11th to 20th	Night	31% 7% 14% 29% 17% 1	3031
	21st to end	Night	29% 5% 12% 30% 21% 3	3586
September	1st to 10th	Night	34% 5% 11% 25% 19% 6%	2009
	11th to 20th	Night	27% 4 8% 29% 29% 3	2200
	21st to end	Night	35% 5% 10% 23% 24% 3	2200
October	1st to 10th	Night	21% 3 7% 33% 35% 2	3590
	11th to 20th	Night	31% 3 10% 24% 31% 1	3875
	21st to end	Night	34% 4 8% 28% 23% 3	4610
November	1st to 10th	Night	38% 4 9% 27% 20% 3	2666
	11th to 20th	Night	45% 4 10% 23% 15% 3	2730
	21st to end	Night	57% 3 10% 21% 8%	2730
December	1st to 10th	Night	46% 4 12% 27% 10% 1	4310
	11th to 20th	Night	62% 4 11% 15% 8% 1	5201
	21st to end	Night	74% 4 9% 9% 3	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	25% 18% 39% 14% 4 1	300
	11th to 20th	Day	26% 19% 37% 14% 2 1	300
	21st to end	Day	29% 19% 32% 15% 4	330
February	1st to 10th	Day	24% 19% 36% 17% 3	300
	11th to 20th	Day	27% 19% 34% 16% 3 1	300
	21st to end	Day	26% 20% 37% 16% 2	249
March	1st to 10th	Day	24% 19% 39% 14% 3	300
	11th to 20th	Day	28% 13% 35% 19% 5%	422
	21st to end	Day	32% 15% 31% 15% 6% 1	550
April	1st to 10th	Day	24% 15% 32% 19% 8% 2	500
	11th to 20th	Day	23% 17% 29% 20% 8% 3	492
	21st to end	Day	27% 13% 31% 18% 9% 2	500
May	1st to 10th	Day	21% 13% 31% 23% 8% 3	503
	11th to 20th	Day	23% 8% 29% 22% 13% 5%	527
	21st to end	Day	14% 8% 30% 24% 16% 8%	677
June	1st to 10th	Day	10% 8% 30% 28% 19% 5%	730
	11th to 20th	Day	12% 6% 26% 32% 19% 5%	730
	21st to end	Day	12% 5% 28% 30% 19% 7%	730
July	1st to 10th	Day	11% 4 18% 27% 25% 14%	721
	11th to 20th	Day	8% 4 22% 31% 23% 13%	718
	21st to end	Day	10% 4 17% 31% 27% 11%	742
August	1st to 10th	Day	7% 4 13% 31% 29% 16%	526
	11th to 20th	Day	11% 3 19% 29% 27% 12%	519
	21st to end	Day	7% 3 15% 32% 32% 11%	583
September	1st to 10th	Day	11% 5% 16% 30% 28% 9%	530
	11th to 20th	Day	9% 2 15% 26% 32% 16%	530
	21st to end	Day	15% 10% 21% 23% 22% 8%	530
October	1st to 10th	Day	12% 7% 23% 31% 18% 8%	530
	11th to 20th	Day	15% 18% 28% 25% 11% 2	444
	21st to end	Day	26% 14% 36% 20% 2 1	363
November	1st to 10th	Day	13% 18% 34% 21% 11% 3	330
	11th to 20th	Day	27% 18% 32% 17% 6% 1	330
	21st to end	Day	30% 13% 36% 17% 4	330
December	1st to 10th	Day	23% 17% 40% 14% 5% 1	306
	11th to 20th	Day	22% 16% 39% 18% 6%	300
	21st to end	Day	31% 18% 35% 14% 3	330
January	1st to 10th	Night	23% 16% 35% 21% 4	1000
	11th to 20th	Night	24% 15% 38% 20% 4	1000
	21st to end	Night	22% 15% 37% 23% 3	1052
February	1st to 10th	Night	27% 13% 33% 25% 2	800
	11th to 20th	Night	21% 15% 37% 24% 3	783
	21st to end	Night	26% 14% 37% 20% 3	660
March	1st to 10th	Night	20% 16% 33% 26% 5%	800
	11th to 20th	Night	19% 12% 38% 25% 6% 1	800
	21st to end	Night	25% 12% 31% 25% 6%	790
April	1st to 10th	Night	18% 12% 39% 25% 6% 1	600
	11th to 20th	Night	21% 13% 33% 25% 8% 1	593
	21st to end	Night	21% 9% 36% 24% 8% 1	600
May	1st to 10th	Night	20% 9% 33% 31% 8%	600
	11th to 20th	Night	21% 6% 25% 32% 15% 1	591
	21st to end	Night	11% 4 24% 40% 18% 2	650
June	1st to 10th	Night	10% 4 26% 44% 16% 1	600
	11th to 20th	Night	11% 4 23% 42% 20% 1	600
	21st to end	Night	10% 3 23% 41% 22% 1	600
July	1st to 10th	Night	9% 2 14% 41% 27% 6%	585
	11th to 20th	Night	7% 4 18% 35% 32% 4	582
	21st to end	Night	8% 2 14% 42% 32% 2	657
August	1st to 10th	Night	8% 1 14% 42% 30% 5%	597
	11th to 20th	Night	6% 3 14% 43% 29% 5%	594
	21st to end	Night	7% 2 15% 35% 36% 5%	660
September	1st to 10th	Night	13% 3 16% 36% 28% 4	609
	11th to 20th	Night	11% 3 14% 36% 33% 3	800
	21st to end	Night	14% 7% 20% 35% 23% 2	800
October	1st to 10th	Night	12% 6% 22% 37% 20% 3	800
	11th to 20th	Night	19% 13% 28% 29% 12% 1	800
	21st to end	Night	22% 13% 32% 26% 7%	880
November	1st to 10th	Night	18% 9% 35% 27% 10% 1	820
	11th to 20th	Night	20% 17% 33% 23% 7%	840
	21st to end	Night	26% 14% 31% 22% 7%	840
December	1st to 10th	Night	25% 12% 37% 22% 4	829
	11th to 20th	Night	24% 14% 33% 23% 6% 1	1000
	21st to end	Night	29% 16% 31% 21% 3	1100

Page generated at 2025-11-30 01:00:55. Version ac07

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