Town Creek Indian Mound
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Town Creek Indian Mound clear sky chart from 2005-11-06 to 2026-04-02.

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	13% 6% 2 6% 4 4 4 4 6% 8% 43%	131646
	Night	14% 6% 2 6% 4 4 4 3 5% 7% 44%	130197
Transparency	Day	38% 7% 12% 19% 18% 6%	135252
	Night	38% 6% 11% 18% 20% 7%	134661
Seeing	Day	16% 11% 26% 25% 16% 6%	17290
	Night	16% 9% 25% 31% 17% 2	27448

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% 3 6% 3 3 3 2 3 5% 53%	5258
	11th to 20th	Day	12% 6% 2 4 3 3 2 2 3 3 61%	5280
	21st to end	Day	17% 8% 3 7% 4 4 4 3 5% 5% 40%	5780
February	1st to 10th	Day	15% 7% 2 5% 3 4 4 3 6% 7% 43%	1890
	11th to 20th	Day	21% 6% 2 4 3 3 3 3 3 6% 45%	1938
	21st to end	Day	19% 7% 2 6% 4 4 3 3 4 5% 41%	1855
March	1st to 10th	Day	20% 7% 2 6% 4 4 4 3 5% 6% 39%	5045
	11th to 20th	Day	10% 5% 2 5% 4 4 3 3 5% 6% 54%	5090
	21st to end	Day	16% 6% 2 5% 4 4 4 3 4 5% 48%	5586
April	1st to 10th	Day	11% 4 1 4 4 3 4 3 7% 8% 51%	2266
	11th to 20th	Day	11% 5% 1 6% 4 4 4 4 5% 7% 48%	2374
	21st to end	Day	12% 4 2 5% 4 5% 4 4 5% 8% 47%	2450
May	1st to 10th	Day	9% 8% 2 7% 6% 5% 6% 5% 7% 10% 35%	5862
	11th to 20th	Day	19% 7% 2 7% 5% 5% 5% 4 7% 8% 30%	5861
	21st to end	Day	12% 5% 2 6% 4 5% 5% 4 6% 8% 42%	6433
June	1st to 10th	Day	9% 6% 2 6% 5% 5% 6% 4 8% 10% 38%	2600
	11th to 20th	Day	9% 5% 2 5% 5% 5% 5% 5% 7% 9% 42%	2600
	21st to end	Day	6% 5% 2 6% 5% 5% 6% 5% 9% 11% 40%	2600
July	1st to 10th	Day	11% 6% 2 8% 6% 6% 6% 5% 8% 11% 32%	5900
	11th to 20th	Day	9% 5% 2 8% 6% 7% 7% 6% 9% 13% 28%	5900
	21st to end	Day	10% 6% 2 7% 5% 6% 6% 5% 8% 11% 33%	6424
August	1st to 10th	Day	23% 7% 3 7% 5% 5% 6% 5% 7% 10% 21%	4234
	11th to 20th	Day	10% 6% 2 7% 6% 6% 7% 6% 8% 10% 33%	4123
	21st to end	Day	6% 4 2 5% 4 4 4 4 7% 11% 50%	4312
September	1st to 10th	Day	8% 5% 2 5% 5% 6% 5% 4 6% 9% 45%	2341
	11th to 20th	Day	13% 5% 2 7% 5% 5% 4 3 5% 8% 43%	2200
	21st to end	Day	18% 7% 2 7% 4 5% 4 3 6% 6% 39%	2200
October	1st to 10th	Day	14% 5% 2 5% 4 3 3 2 5% 6% 51%	2017
	11th to 20th	Day	11% 4 1 4 4 3 4 3 3 5% 58%	2000
	21st to end	Day	14% 4 2 5% 3 3 3 3 3 4 57%	2200
November	1st to 10th	Day	12% 5% 2 4 3 3 3 3 4 5% 55%	2057
	11th to 20th	Day	14% 4 2 4 2 3 3 3 4 6% 54%	2032
	21st to end	Day	13% 5% 2 4 4 3 4 3 5% 6% 50%	1890
December	1st to 10th	Day	15% 7% 2 5% 3 3 3 2 4 5% 52%	3020
	11th to 20th	Day	18% 5% 2 6% 4 4 3 3 4 6% 45%	3463
	21st to end	Day	18% 6% 2 5% 4 3 3 3 4 6% 46%	4565
January	1st to 10th	Night	12% 6% 2 5% 3 3 2 2 3 4 56%	7635
	11th to 20th	Night	13% 6% 2 5% 3 3 3 2 4 4 55%	7680
	21st to end	Night	18% 8% 2 6% 4 3 3 3 4 5% 43%	8401
February	1st to 10th	Night	16% 6% 2 6% 4 3 3 3 5% 5% 46%	2730
	11th to 20th	Night	20% 7% 2 5% 4 3 3 3 4 6% 42%	2565
	21st to end	Night	16% 7% 2 4 3 3 4 3 6% 6% 46%	1950
March	1st to 10th	Night	20% 7% 3 7% 3 3 3 2 3 5% 42%	5028
	11th to 20th	Night	11% 4 2 4 3 3 3 3 5% 6% 54%	5090
	21st to end	Night	15% 4 2 5% 4 4 4 3 5% 6% 49%	5588
April	1st to 10th	Night	14% 5% 2 4 3 3 3 4 6% 7% 49%	2155
	11th to 20th	Night	12% 5% 2 5% 4 4 4 3 5% 6% 51%	1975
	21st to end	Night	11% 4 1 5% 5% 5% 4 4 6% 7% 48%	1967
May	1st to 10th	Night	12% 7% 3 7% 4 4 4 3 6% 9% 41%	4033
	11th to 20th	Night	19% 7% 3 7% 5% 4 4 4 6% 9% 33%	4032
	21st to end	Night	13% 5% 2 6% 4 4 4 4 7% 9% 41%	4421
June	1st to 10th	Night	11% 6% 2 7% 7% 5% 5% 6% 8% 9% 35%	1800
	11th to 20th	Night	10% 6% 2 7% 7% 6% 6% 5% 7% 9% 37%	1800
	21st to end	Night	8% 5% 3 7% 5% 5% 5% 5% 9% 12% 37%	1800
July	1st to 10th	Night	13% 6% 3 9% 6% 5% 6% 5% 8% 10% 28%	4058
	11th to 20th	Night	11% 6% 3 8% 6% 7% 7% 5% 9% 12% 26%	4057
	21st to end	Night	14% 8% 3 9% 6% 5% 6% 5% 7% 10% 26%	4427
August	1st to 10th	Night	24% 8% 3 7% 5% 5% 6% 4 6% 9% 24%	2915
	11th to 20th	Night	11% 5% 3 8% 6% 6% 6% 5% 8% 10% 34%	2890
	21st to end	Night	5% 4 2 5% 4 5% 4 4 7% 9% 51%	3586
September	1st to 10th	Night	9% 5% 2 5% 4 5% 5% 4 6% 8% 47%	2054
	11th to 20th	Night	13% 7% 3 7% 4 4 3 4 5% 7% 43%	2200
	21st to end	Night	17% 7% 2 7% 5% 5% 4 3 5% 7% 38%	2200
October	1st to 10th	Night	12% 6% 2 6% 4 3 4 3 4 6% 50%	2381
	11th to 20th	Night	13% 5% 2 4 3 3 2 3 4 5% 55%	2400
	21st to end	Night	12% 6% 2 5% 3 2 3 3 3 5% 56%	2640
November	1st to 10th	Night	13% 5% 2 5% 3 3 3 2 4 5% 54%	2461
	11th to 20th	Night	11% 6% 3 5% 4 3 3 2 4 6% 52%	2583
	21st to end	Night	13% 5% 2 4 3 3 3 4 5% 6% 51%	2730
December	1st to 10th	Night	15% 7% 2 4 3 3 3 3 5% 5% 52%	4380
	11th to 20th	Night	18% 7% 3 7% 5% 4 4 3 4 5% 42%	4952
	21st to end	Night	19% 5% 2 5% 3 4 3 3 4 5% 47%	6633

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	36% 3 8% 21% 26% 6%	5259
	11th to 20th	Day	30% 3 4 13% 37% 13%	5280
	21st to end	Day	46% 3 4 18% 20% 9%	5780
February	1st to 10th	Day	39% 5% 10% 21% 20% 6%	1890
	11th to 20th	Day	42% 4 7% 18% 22% 7%	1947
	21st to end	Day	46% 4 7% 17% 19% 7%	1855
March	1st to 10th	Day	45% 5% 7% 14% 19% 11%	5045
	11th to 20th	Day	31% 5% 7% 14% 27% 16%	5090
	21st to end	Day	39% 4 8% 20% 21% 8%	5586
April	1st to 10th	Day	30% 5% 12% 21% 26% 7%	2266
	11th to 20th	Day	34% 5% 11% 20% 21% 9%	2374
	21st to end	Day	34% 7% 14% 22% 19% 4	2450
May	1st to 10th	Day	41% 9% 17% 21% 11% 1	5897
	11th to 20th	Day	50% 8% 12% 18% 11% 1	5865
	21st to end	Day	37% 7% 13% 20% 19% 3	6447
June	1st to 10th	Day	37% 10% 16% 21% 14% 1	2600
	11th to 20th	Day	35% 10% 18% 20% 15% 2	2600
	21st to end	Day	32% 13% 16% 22% 15% 2	2600
July	1st to 10th	Day	43% 11% 17% 19% 8% 1	5835
	11th to 20th	Day	42% 15% 28% 12% 3 1	5831
	21st to end	Day	43% 11% 17% 20% 9%	6240
August	1st to 10th	Day	56% 10% 17% 12% 5%	4221
	11th to 20th	Day	42% 11% 17% 19% 9% 1	4162
	21st to end	Day	28% 8% 14% 32% 16% 2	4312
September	1st to 10th	Day	34% 9% 15% 20% 17% 5%	2341
	11th to 20th	Day	39% 7% 13% 16% 21% 4	2200
	21st to end	Day	44% 7% 9% 19% 15% 5%	2200
October	1st to 10th	Day	32% 5% 7% 20% 26% 10%	3277
	11th to 20th	Day	19% 3 5% 20% 27% 26%	3240
	21st to end	Day	26% 3 5% 24% 24% 18%	3538
November	1st to 10th	Day	32% 4 7% 19% 28% 9%	2057
	11th to 20th	Day	31% 4 9% 21% 27% 8%	2032
	21st to end	Day	35% 5% 8% 22% 24% 7%	1890
December	1st to 10th	Day	37% 3 7% 18% 27% 8%	3020
	11th to 20th	Day	40% 5% 9% 17% 22% 6%	3460
	21st to end	Day	40% 4 9% 25% 20% 2	4565
January	1st to 10th	Night	33% 4 9% 21% 28% 6%	7636
	11th to 20th	Night	33% 3 5% 14% 34% 10%	7680
	21st to end	Night	45% 3 4 17% 23% 9%	8401
February	1st to 10th	Night	41% 4 9% 19% 20% 6%	2730
	11th to 20th	Night	44% 3 9% 16% 22% 7%	2567
	21st to end	Night	38% 4 9% 17% 23% 8%	1950
March	1st to 10th	Night	45% 4 6% 12% 25% 7%	5028
	11th to 20th	Night	30% 4 7% 13% 27% 18%	5090
	21st to end	Night	37% 5% 8% 21% 22% 7%	5588
April	1st to 10th	Night	34% 5% 10% 21% 23% 8%	2155
	11th to 20th	Night	34% 5% 9% 22% 21% 9%	1975
	21st to end	Night	34% 6% 13% 22% 19% 5%	1967
May	1st to 10th	Night	39% 7% 17% 20% 14% 2	4060
	11th to 20th	Night	47% 8% 16% 17% 12% 1	4033
	21st to end	Night	36% 8% 14% 25% 15% 2	4429
June	1st to 10th	Night	41% 10% 15% 20% 12% 2	1800
	11th to 20th	Night	41% 11% 16% 19% 12% 1	1800
	21st to end	Night	35% 14% 16% 21% 12% 3	1800
July	1st to 10th	Night	47% 12% 18% 15% 8% 1	4015
	11th to 20th	Night	49% 16% 22% 10% 3 1	4006
	21st to end	Night	51% 10% 15% 17% 6%	4297
August	1st to 10th	Night	55% 9% 17% 14% 4 1	2904
	11th to 20th	Night	40% 11% 22% 20% 6% 1	2917
	21st to end	Night	27% 8% 14% 27% 20% 4	3586
September	1st to 10th	Night	35% 8% 14% 22% 15% 6%	2054
	11th to 20th	Night	40% 8% 13% 17% 20% 3	2200
	21st to end	Night	45% 7% 13% 16% 15% 4	2200
October	1st to 10th	Night	34% 6% 9% 20% 26% 6%	3901
	11th to 20th	Night	22% 4 6% 18% 29% 22%	3899
	21st to end	Night	26% 3 6% 22% 25% 17%	4252
November	1st to 10th	Night	33% 5% 7% 19% 25% 12%	2461
	11th to 20th	Night	34% 4 7% 17% 27% 12%	2583
	21st to end	Night	33% 4 7% 22% 25% 8%	2730
December	1st to 10th	Night	36% 4 7% 18% 27% 9%	4380
	11th to 20th	Night	45% 4 9% 16% 18% 8%	4954
	21st to end	Night	39% 4 11% 23% 21% 2	6633

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	22% 25% 36% 15% 2	330
	11th to 20th	Day	24% 24% 37% 12% 3	330
	21st to end	Day	23% 25% 38% 12% 2	363
February	1st to 10th	Day	20% 18% 44% 14% 3	330
	11th to 20th	Day	36% 22% 33% 8% 1	330
	21st to end	Day	27% 22% 31% 17% 3 1	398
March	1st to 10th	Day	22% 20% 30% 22% 6%	540
	11th to 20th	Day	21% 22% 37% 15% 5%	540
	21st to end	Day	21% 20% 34% 19% 5% 1	594
April	1st to 10th	Day	22% 20% 31% 19% 8% 1	504
	11th to 20th	Day	14% 18% 33% 20% 13% 2	492
	21st to end	Day	15% 12% 29% 28% 13% 3	500
May	1st to 10th	Day	13% 17% 33% 23% 10% 4	503
	11th to 20th	Day	17% 9% 24% 27% 20% 4	527
	21st to end	Day	17% 7% 21% 24% 23% 7%	573
June	1st to 10th	Day	11% 4 23% 34% 22% 6%	530
	11th to 20th	Day	9% 5% 22% 28% 25% 10%	530
	21st to end	Day	7% 3 16% 35% 30% 8%	530
July	1st to 10th	Day	10% 3 13% 28% 30% 17%	525
	11th to 20th	Day	9% 1 11% 28% 35% 15%	524
	21st to end	Day	8% 2 12% 34% 32% 13%	576
August	1st to 10th	Day	18% 4 15% 28% 23% 12%	526
	11th to 20th	Day	11% 3 13% 33% 25% 14%	519
	21st to end	Day	13% 2 14% 30% 25% 16%	583
September	1st to 10th	Day	12% 3 17% 29% 26% 14%	530
	11th to 20th	Day	15% 4 16% 29% 25% 11%	530
	21st to end	Day	19% 8% 20% 30% 18% 5%	530
October	1st to 10th	Day	15% 8% 22% 27% 22% 7%	530
	11th to 20th	Day	12% 9% 27% 29% 18% 5%	530
	21st to end	Day	15% 11% 28% 27% 15% 5%	583
November	1st to 10th	Day	17% 10% 31% 29% 11% 2	535
	11th to 20th	Day	17% 17% 33% 21% 10% 1	472
	21st to end	Day	14% 18% 35% 22% 9% 2	330
December	1st to 10th	Day	28% 14% 38% 16% 3	330
	11th to 20th	Day	22% 15% 34% 22% 8% 1	330
	21st to end	Day	25% 16% 33% 19% 6% 2	363
January	1st to 10th	Night	22% 15% 30% 28% 5%	840
	11th to 20th	Night	20% 15% 33% 29% 4	840
	21st to end	Night	20% 13% 35% 30% 2	924
February	1st to 10th	Night	19% 14% 35% 28% 4	840
	11th to 20th	Night	26% 17% 37% 19% 2	823
	21st to end	Night	20% 17% 34% 25% 4	692
March	1st to 10th	Night	19% 14% 33% 29% 5%	840
	11th to 20th	Night	18% 16% 33% 25% 8%	840
	21st to end	Night	18% 15% 36% 26% 5%	924
April	1st to 10th	Night	18% 16% 33% 26% 7%	805
	11th to 20th	Night	15% 14% 31% 28% 12%	791
	21st to end	Night	14% 8% 30% 37% 11%	767
May	1st to 10th	Night	12% 11% 31% 35% 11% 1	600
	11th to 20th	Night	15% 7% 23% 35% 20% 1	591
	21st to end	Night	13% 3 16% 39% 29% 1	650
June	1st to 10th	Night	11% 2 21% 38% 25% 3	600
	11th to 20th	Night	12% 4 16% 32% 32% 5%	600
	21st to end	Night	10% 2 14% 38% 34% 3	600
July	1st to 10th	Night	10% 2 12% 31% 39% 6%	585
	11th to 20th	Night	10% 2 8% 33% 40% 8%	582
	21st to end	Night	7% 2 12% 36% 37% 7%	657
August	1st to 10th	Night	13% 3 11% 32% 35% 6%	597
	11th to 20th	Night	13% 1 10% 34% 37% 6%	596
	21st to end	Night	10% 1 13% 32% 38% 5%	880
September	1st to 10th	Night	10% 3 13% 33% 37% 6%	800
	11th to 20th	Night	15% 4 15% 30% 33% 5%	800
	21st to end	Night	19% 5% 19% 33% 22% 2	800
October	1st to 10th	Night	14% 6% 19% 28% 28% 5%	800
	11th to 20th	Night	15% 8% 24% 33% 18% 3	800
	21st to end	Night	16% 10% 21% 30% 21% 1	880
November	1st to 10th	Night	16% 8% 25% 33% 16% 2	820
	11th to 20th	Night	14% 13% 29% 32% 11%	840
	21st to end	Night	16% 11% 30% 30% 12% 1	840
December	1st to 10th	Night	23% 11% 28% 32% 5%	840
	11th to 20th	Night	20% 10% 29% 33% 9%	840
	21st to end	Night	24% 12% 25% 31% 8%	924

Page generated at 2026-03-30 02:18:42. Version ac07

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