Atchison
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Atchison clear sky chart from 2005-11-06 to 2026-08-15.

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% 7% 3 6% 4 4 4 3 5% 7% 46%	143181
	Night	11% 7% 2 6% 4 4 4 3 5% 6% 48%	139051
Transparency	Day	25% 35% 8% 18% 12% 2	146793
	Night	25% 34% 8% 18% 13% 2	143506
Seeing	Day	15% 9% 30% 28% 15% 4	18186
	Night	14% 9% 32% 33% 12% 1	27953

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	13% 9% 3 9% 4 4 4 3 5% 7% 40%	5289
	11th to 20th	Day	5% 8% 3 8% 7% 7% 6% 4 4 6% 42%	5310
	21st to end	Day	11% 13% 5% 9% 5% 4 3 3 4 5% 38%	5812
February	1st to 10th	Day	12% 11% 4 9% 6% 4 4 3 5% 7% 37%	1890
	11th to 20th	Day	11% 10% 4 7% 4 4 4 2 5% 7% 40%	1844
	21st to end	Day	10% 8% 4 7% 3 3 3 3 5% 6% 48%	1773
March	1st to 10th	Day	15% 8% 2 5% 3 3 3 2 3 5% 51%	5046
	11th to 20th	Day	11% 7% 2 4 3 3 3 3 5% 6% 53%	5090
	21st to end	Day	13% 11% 5% 8% 5% 4 4 4 5% 7% 34%	5583
April	1st to 10th	Day	15% 9% 2 6% 4 3 3 3 5% 6% 44%	2408
	11th to 20th	Day	15% 8% 3 6% 4 4 4 3 5% 6% 41%	2494
	21st to end	Day	21% 8% 3 7% 4 3 4 3 5% 6% 36%	2725
May	1st to 10th	Day	15% 7% 2 5% 4 4 4 3 5% 6% 46%	7617
	11th to 20th	Day	14% 5% 2 5% 4 4 4 3 5% 7% 48%	7627
	21st to end	Day	19% 7% 2 6% 4 4 4 3 5% 7% 39%	8569
June	1st to 10th	Day	7% 4 2 5% 4 5% 5% 4 7% 8% 49%	2940
	11th to 20th	Day	8% 4 2 5% 5% 4 4 4 6% 9% 47%	2940
	21st to end	Day	8% 4 2 5% 4 4 5% 5% 6% 9% 48%	2934
July	1st to 10th	Day	10% 4 1 6% 4 4 4 4 7% 9% 47%	7680
	11th to 20th	Day	7% 4 2 6% 3 4 4 3 5% 8% 54%	7680
	21st to end	Day	11% 5% 3 6% 4 4 5% 4 6% 9% 43%	8337
August	1st to 10th	Day	6% 4 2 5% 4 4 4 4 6% 9% 52%	4364
	11th to 20th	Day	12% 5% 2 6% 4 4 4 4 5% 7% 47%	4224
	21st to end	Day	7% 3 2 5% 4 4 4 3 5% 8% 54%	4458
September	1st to 10th	Day	12% 4 2 4 3 3 3 3 6% 6% 53%	2387
	11th to 20th	Day	9% 5% 2 6% 5% 4 4 4 5% 6% 49%	2200
	21st to end	Day	9% 4 1 4 4 3 4 3 4 6% 57%	2200
October	1st to 10th	Day	12% 6% 1 5% 3 3 3 3 5% 6% 54%	2005
	11th to 20th	Day	12% 5% 2 5% 3 2 3 3 4 6% 55%	2000
	21st to end	Day	15% 7% 2 5% 4 3 3 3 4 6% 48%	2200
November	1st to 10th	Day	9% 6% 1 4 3 3 4 2 5% 7% 55%	2002
	11th to 20th	Day	12% 6% 2 5% 3 3 3 3 5% 5% 53%	1819
	21st to end	Day	15% 11% 3 5% 2 2 3 3 4 6% 45%	1680
December	1st to 10th	Day	6% 5% 2 6% 5% 4 4 4 5% 5% 55%	2690
	11th to 20th	Day	11% 8% 3 7% 4 3 4 3 3 5% 49%	3088
	21st to end	Day	18% 14% 7% 12% 5% 3 3 3 4 4 26%	4276
January	1st to 10th	Night	12% 8% 4 14% 5% 4 4 2 4 5% 37%	7634
	11th to 20th	Night	7% 8% 3 7% 3 4 5% 4 5% 5% 49%	7680
	21st to end	Night	13% 12% 4 10% 4 5% 3 3 4 5% 38%	8402
February	1st to 10th	Night	11% 12% 4 8% 4 4 4 3 5% 5% 40%	2730
	11th to 20th	Night	11% 9% 3 8% 5% 3 5% 3 5% 7% 42%	2663
	21st to end	Night	10% 8% 2 6% 3 4 3 4 5% 6% 49%	2051
March	1st to 10th	Night	16% 7% 3 5% 2 3 3 3 3 5% 51%	5029
	11th to 20th	Night	10% 5% 2 4 3 3 3 3 4 7% 56%	5090
	21st to end	Night	15% 8% 3 7% 5% 4 4 4 6% 7% 37%	5588
April	1st to 10th	Night	12% 6% 2 6% 3 3 3 3 5% 7% 49%	2210
	11th to 20th	Night	13% 7% 3 5% 4 3 3 3 4 6% 49%	2075
	21st to end	Night	17% 6% 2 7% 4 4 4 3 4 7% 42%	1892
May	1st to 10th	Night	14% 6% 2 6% 4 3 3 3 4 6% 48%	5266
	11th to 20th	Night	14% 5% 2 4 3 3 4 3 4 7% 52%	5265
	21st to end	Night	18% 5% 2 6% 3 4 4 3 5% 6% 45%	5598
June	1st to 10th	Night	6% 3 1 4 3 4 4 5% 5% 9% 55%	1680
	11th to 20th	Night	6% 4 1 5% 4 4 5% 4 6% 8% 55%	1680
	21st to end	Night	5% 2 1 5% 3 3 4 4 4 9% 60%	1680
July	1st to 10th	Night	7% 4 2 5% 4 4 4 4 6% 9% 51%	5306
	11th to 20th	Night	5% 3 2 4 4 3 4 4 6% 8% 58%	5307
	21st to end	Night	10% 4 2 6% 4 5% 4 4 7% 10% 44%	5770
August	1st to 10th	Night	3 2 1 4 3 3 4 4 6% 10% 60%	3016
	11th to 20th	Night	12% 4 2 5% 4 3 4 3 4 6% 53%	2924
	21st to end	Night	6% 4 2 5% 4 3 3 3 5% 8% 58%	3443
September	1st to 10th	Night	10% 4 2 4 3 3 4 3 4 6% 57%	2010
	11th to 20th	Night	9% 4 2 5% 4 3 5% 3 6% 7% 54%	2200
	21st to end	Night	7% 4 2 4 3 3 3 3 4 6% 60%	2200
October	1st to 10th	Night	12% 5% 2 4 3 2 3 3 4 5% 57%	2374
	11th to 20th	Night	13% 4 2 4 3 3 3 3 4 6% 56%	2400
	21st to end	Night	16% 8% 2 5% 3 3 3 2 3 4 53%	2640
November	1st to 10th	Night	8% 4 2 3 3 3 3 3 4 6% 61%	2513
	11th to 20th	Night	11% 5% 2 4 3 3 4 3 4 6% 55%	2798
	21st to end	Night	13% 8% 2 5% 3 3 3 3 4 5% 51%	2940
December	1st to 10th	Night	6% 6% 2 4 3 4 4 3 4 6% 57%	4720
	11th to 20th	Night	11% 7% 3 7% 4 3 4 3 5% 7% 47%	5339
	21st to end	Night	20% 15% 5% 9% 3 3 3 3 3 4 31%	6938

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	38% 21% 8% 23% 9% 1	5290
	11th to 20th	Day	35% 22% 8% 18% 12% 4	5310
	21st to end	Day	40% 23% 9% 15% 13% 1	5812
February	1st to 10th	Day	21% 59% 7% 8% 3 1	1890
	11th to 20th	Day	19% 58% 5% 9% 8% 1	1853
	21st to end	Day	15% 58% 4 10% 11% 2	1773
March	1st to 10th	Day	26% 28% 6% 15% 20% 5%	5046
	11th to 20th	Day	18% 28% 7% 16% 26% 5%	5090
	21st to end	Day	33% 30% 12% 20% 4 1	5585
April	1st to 10th	Day	19% 59% 5% 9% 7% 1	2408
	11th to 20th	Day	17% 60% 6% 9% 7% 1	2494
	21st to end	Day	21% 60% 4 11% 4	2725
May	1st to 10th	Day	30% 24% 7% 24% 15% 1	7655
	11th to 20th	Day	27% 24% 8% 20% 18% 2	7631
	21st to end	Day	36% 24% 7% 21% 12% 1	8583
June	1st to 10th	Day	13% 60% 6% 11% 9% 1	2940
	11th to 20th	Day	13% 60% 6% 13% 7% 1	2940
	21st to end	Day	14% 60% 8% 13% 5%	2934
July	1st to 10th	Day	26% 23% 11% 26% 12% 1	7616
	11th to 20th	Day	22% 23% 11% 24% 15% 5%	7611
	21st to end	Day	30% 24% 13% 25% 6% 1	8155
August	1st to 10th	Day	18% 37% 11% 20% 14% 1	4350
	11th to 20th	Day	24% 37% 12% 17% 9% 1	4263
	21st to end	Day	20% 38% 12% 21% 7% 3	4457
September	1st to 10th	Day	12% 58% 7% 13% 9% 2	2387
	11th to 20th	Day	13% 59% 5% 14% 8% 2	2200
	21st to end	Day	16% 57% 4 12% 10% 1	2200
October	1st to 10th	Day	11% 35% 3 11% 36% 4	3265
	11th to 20th	Day	7% 35% 3 18% 29% 7%	3240
	21st to end	Day	19% 36% 7% 20% 16% 2	3538
November	1st to 10th	Day	17% 53% 6% 13% 8% 3	2002
	11th to 20th	Day	17% 54% 4 13% 11% 2	1819
	21st to end	Day	21% 54% 5% 13% 7%	1680
December	1st to 10th	Day	17% 36% 9% 25% 13%	2690
	11th to 20th	Day	26% 31% 9% 26% 8% 1	3085
	21st to end	Day	52% 26% 8% 10% 4 1	4276
January	1st to 10th	Night	43% 22% 10% 16% 8% 1	7635
	11th to 20th	Night	29% 21% 8% 23% 16% 3	7680
	21st to end	Night	40% 22% 9% 13% 12% 3	8402
February	1st to 10th	Night	19% 59% 7% 9% 6% 1	2730
	11th to 20th	Night	19% 58% 6% 11% 6% 1	2664
	21st to end	Night	14% 59% 3 9% 12% 3	2051
March	1st to 10th	Night	28% 28% 5% 16% 20% 3	5029
	11th to 20th	Night	17% 28% 3 19% 26% 7%	5090
	21st to end	Night	31% 30% 12% 20% 6% 2	5588
April	1st to 10th	Night	18% 60% 5% 9% 8% 1	2210
	11th to 20th	Night	15% 60% 6% 10% 7% 1	2075
	21st to end	Night	19% 59% 4 10% 7% 1	1892
May	1st to 10th	Night	29% 24% 8% 22% 15% 2	5293
	11th to 20th	Night	26% 23% 8% 19% 19% 5%	5266
	21st to end	Night	33% 24% 7% 22% 14%	5609
June	1st to 10th	Night	10% 60% 7% 13% 9% 1	1680
	11th to 20th	Night	12% 60% 5% 14% 9% 1	1680
	21st to end	Night	9% 59% 8% 16% 7% 1	1680
July	1st to 10th	Night	24% 23% 12% 21% 19% 2	5263
	11th to 20th	Night	20% 23% 11% 24% 16% 5%	5256
	21st to end	Night	28% 24% 14% 28% 6%	5641
August	1st to 10th	Night	13% 36% 14% 17% 19% 2	3006
	11th to 20th	Night	23% 37% 9% 19% 12% 1	2951
	21st to end	Night	18% 37% 10% 24% 9% 1	3443
September	1st to 10th	Night	13% 58% 5% 11% 9% 3	2010
	11th to 20th	Night	10% 58% 6% 14% 11% 1	2200
	21st to end	Night	14% 57% 4 12% 12% 1	2200
October	1st to 10th	Night	13% 35% 3 10% 36% 3	3881
	11th to 20th	Night	9% 35% 3 20% 24% 9%	3899
	21st to end	Night	21% 36% 4 21% 17% 1	4252
November	1st to 10th	Night	13% 54% 6% 14% 11% 2	2513
	11th to 20th	Night	14% 54% 5% 13% 12% 3	2798
	21st to end	Night	20% 54% 5% 12% 9%	2940
December	1st to 10th	Night	16% 35% 10% 25% 14%	4720
	11th to 20th	Night	25% 31% 9% 22% 11% 1	5341
	21st to end	Night	48% 26% 7% 14% 4 1	6938

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% 13% 38% 19% 8%	330
	11th to 20th	Day	18% 21% 42% 16% 3	330
	21st to end	Day	15% 11% 47% 22% 4	363
February	1st to 10th	Day	18% 18% 43% 18% 3 1	330
	11th to 20th	Day	18% 18% 43% 15% 6%	330
	21st to end	Day	13% 19% 45% 18% 5%	273
March	1st to 10th	Day	17% 16% 45% 19% 2	330
	11th to 20th	Day	28% 15% 32% 19% 5% 1	330
	21st to end	Day	31% 19% 34% 12% 4 1	363
April	1st to 10th	Day	26% 16% 36% 18% 5%	428
	11th to 20th	Day	21% 13% 39% 20% 5% 1	532
	21st to end	Day	24% 13% 36% 18% 9% 1	745
May	1st to 10th	Day	19% 12% 37% 22% 8% 2	753
	11th to 20th	Day	18% 10% 29% 29% 12% 2	775
	21st to end	Day	19% 7% 30% 27% 15% 3	844
June	1st to 10th	Day	7% 6% 23% 33% 25% 6%	780
	11th to 20th	Day	8% 4 32% 34% 17% 5%	780
	21st to end	Day	9% 6% 34% 35% 14% 2	780
July	1st to 10th	Day	11% 2 17% 33% 29% 8%	771
	11th to 20th	Day	6% 3 18% 38% 26% 8%	768
	21st to end	Day	11% 2 16% 36% 28% 6%	849
August	1st to 10th	Day	8% 3 19% 37% 27% 6%	776
	11th to 20th	Day	10% 3 18% 39% 24% 7%	736
	21st to end	Day	10% 2 15% 34% 30% 9%	677
September	1st to 10th	Day	14% 2 17% 36% 26% 5%	517
	11th to 20th	Day	8% 4 22% 36% 24% 7%	330
	21st to end	Day	14% 5% 26% 33% 15% 7%	330
October	1st to 10th	Day	13% 6% 28% 28% 19% 5%	330
	11th to 20th	Day	9% 15% 43% 25% 7% 2	330
	21st to end	Day	21% 13% 36% 21% 7% 1	363
November	1st to 10th	Day	15% 9% 42% 24% 7% 2	330
	11th to 20th	Day	15% 14% 40% 21% 9% 1	330
	21st to end	Day	22% 12% 34% 23% 8% 1	330
December	1st to 10th	Day	9% 16% 42% 25% 7% 2	330
	11th to 20th	Day	20% 16% 36% 21% 7% 1	330
	21st to end	Day	22% 18% 38% 20% 2	363
January	1st to 10th	Night	13% 13% 38% 28% 7%	1050
	11th to 20th	Night	15% 15% 40% 24% 6%	1050
	21st to end	Night	15% 11% 42% 29% 3	1155
February	1st to 10th	Night	16% 13% 42% 26% 3	1050
	11th to 20th	Night	17% 14% 38% 28% 4	1029
	21st to end	Night	15% 14% 43% 23% 5% 1	667
March	1st to 10th	Night	15% 13% 42% 25% 5%	630
	11th to 20th	Night	19% 10% 37% 28% 6%	630
	21st to end	Night	25% 11% 38% 23% 3	693
April	1st to 10th	Night	15% 12% 42% 25% 6%	630
	11th to 20th	Night	16% 17% 35% 28% 5%	623
	21st to end	Night	19% 8% 39% 27% 6% 1	630
May	1st to 10th	Night	17% 8% 33% 34% 8%	630
	11th to 20th	Night	18% 6% 30% 34% 12%	621
	21st to end	Night	13% 5% 28% 39% 13% 2	683
June	1st to 10th	Night	7% 3 23% 43% 23% 1	630
	11th to 20th	Night	8% 4 26% 46% 15% 2	630
	21st to end	Night	6% 5% 34% 41% 15%	630
July	1st to 10th	Night	7% 1 15% 43% 31% 2	615
	11th to 20th	Night	3 1 16% 49% 29% 3	612
	21st to end	Night	8% 2 13% 48% 27% 1	690
August	1st to 10th	Night	5% 2 15% 48% 29% 2	627
	11th to 20th	Night	7% 3 13% 46% 28% 3	606
	21st to end	Night	7% 2 13% 43% 31% 3	660
September	1st to 10th	Night	12% 3 19% 40% 25% 3	600
	11th to 20th	Night	9% 1 21% 44% 23% 2	600
	21st to end	Night	8% 3 25% 43% 20% 2	600
October	1st to 10th	Night	14% 6% 27% 33% 19% 2	774
	11th to 20th	Night	15% 8% 39% 30% 8% 1	800
	21st to end	Night	19% 10% 35% 26% 9%	880
November	1st to 10th	Night	9% 11% 33% 37% 10% 1	873
	11th to 20th	Night	13% 12% 38% 30% 7%	1050
	21st to end	Night	17% 11% 36% 28% 8%	1050
December	1st to 10th	Night	14% 12% 35% 32% 6% 1	1050
	11th to 20th	Night	18% 9% 41% 27% 5%	1050
	21st to end	Night	18% 14% 36% 27% 4	1155

Page generated at 2026-08-12 02:37:17. Version ac07

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