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 2025-04-11.

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	11% 7% 3 6% 4 4 4 3 5% 7% 46%	113544
	Night	11% 7% 3 6% 4 3 4 3 5% 6% 48%	114939
Transparency	Day	22% 42% 7% 16% 11% 2	117197
	Night	22% 40% 7% 16% 12% 2	119415
Seeing	Day	15% 9% 30% 28% 15% 4	16187
	Night	14% 9% 32% 33% 12% 1	26228

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% 9% 4 10% 4 4 4 3 6% 7% 36%	4077
	11th to 20th	Day	7% 9% 3 9% 6% 7% 6% 3 3 5% 42%	4080
	21st to end	Day	12% 12% 6% 10% 5% 4 3 3 4 5% 35%	4488
February	1st to 10th	Day	12% 11% 4 9% 6% 4 4 2 5% 7% 36%	1800
	11th to 20th	Day	11% 10% 4 7% 4 4 4 2 5% 7% 40%	1754
	21st to end	Day	11% 8% 4 7% 3 3 3 3 5% 6% 47%	1691
March	1st to 10th	Day	15% 8% 2 5% 3 3 3 2 3 5% 52%	4936
	11th to 20th	Day	11% 7% 2 4 3 3 3 3 5% 6% 52%	4980
	21st to end	Day	13% 11% 5% 8% 5% 4 4 4 5% 7% 34%	5462
April	1st to 10th	Day	14% 8% 2 6% 4 3 3 3 4 6% 45%	2293
	11th to 20th	Day	15% 9% 3 6% 4 4 4 3 5% 6% 41%	2254
	21st to end	Day	21% 7% 2 6% 4 3 4 3 6% 6% 37%	2465
May	1st to 10th	Day	15% 8% 3 6% 5% 4 4 3 5% 7% 41%	4082
	11th to 20th	Day	16% 8% 2 6% 4 4 4 3 5% 8% 40%	4082
	21st to end	Day	13% 6% 2 5% 4 3 4 3 5% 8% 45%	4570
June	1st to 10th	Day	7% 4 2 4 5% 5% 5% 4 6% 8% 50%	2660
	11th to 20th	Day	8% 4 2 6% 5% 4 4 4 7% 9% 47%	2660
	21st to end	Day	7% 4 2 5% 4 4 5% 5% 7% 9% 49%	2655
July	1st to 10th	Day	12% 6% 2 6% 4 4 4 4 7% 9% 43%	4120
	11th to 20th	Day	7% 4 2 5% 4 4 4 3 5% 8% 55%	4120
	21st to end	Day	7% 3 2 4 4 4 4 4 6% 10% 52%	4465
August	1st to 10th	Day	6% 4 2 5% 4 4 4 4 6% 9% 52%	4104
	11th to 20th	Day	12% 5% 2 6% 4 4 4 4 5% 7% 47%	4041
	21st to end	Day	7% 3 2 4 4 4 4 3 5% 9% 54%	4322
September	1st to 10th	Day	12% 4 2 4 3 3 3 3 6% 6% 54%	2268
	11th to 20th	Day	9% 5% 2 6% 5% 4 4 4 5% 6% 50%	2090
	21st to end	Day	9% 4 1 4 4 3 4 3 4 6% 57%	2090
October	1st to 10th	Day	12% 6% 1 5% 3 3 3 3 5% 6% 53%	1905
	11th to 20th	Day	12% 6% 2 5% 2 2 3 3 4 6% 56%	1900
	21st to end	Day	14% 7% 2 5% 4 3 3 3 4 6% 49%	2090
November	1st to 10th	Day	10% 6% 2 4 3 4 4 2 5% 7% 54%	1905
	11th to 20th	Day	13% 6% 2 4 3 3 3 3 5% 5% 52%	1733
	21st to end	Day	14% 11% 2 5% 2 2 3 3 4 7% 46%	1600
December	1st to 10th	Day	6% 5% 2 6% 5% 4 4 4 5% 5% 55%	2610
	11th to 20th	Day	11% 8% 3 7% 4 3 4 3 3 5% 49%	3008
	21st to end	Day	19% 14% 7% 12% 5% 3 3 3 4 4 26%	4184
January	1st to 10th	Night	11% 8% 4 16% 6% 4 4 3 4 5% 34%	5888
	11th to 20th	Night	8% 8% 3 8% 4 5% 5% 4 4 5% 45%	5900
	21st to end	Night	14% 11% 4 10% 4 4 3 3 3 5% 39%	6490
February	1st to 10th	Night	11% 12% 4 8% 4 4 4 3 5% 5% 39%	2600
	11th to 20th	Night	11% 9% 3 8% 5% 3 5% 3 5% 7% 42%	2533
	21st to end	Night	11% 8% 2 6% 3 4 3 4 5% 6% 48%	1956
March	1st to 10th	Night	15% 7% 3 5% 2 3 3 3 4 5% 52%	4919
	11th to 20th	Night	10% 5% 1 4 3 3 3 3 5% 7% 57%	4980
	21st to end	Night	15% 8% 3 7% 5% 4 4 4 6% 7% 36%	5467
April	1st to 10th	Night	11% 6% 2 6% 3 3 3 3 5% 7% 50%	2105
	11th to 20th	Night	13% 8% 3 5% 4 3 3 3 4 6% 48%	1881
	21st to end	Night	17% 6% 2 6% 4 4 4 3 4 7% 43%	1712
May	1st to 10th	Night	16% 6% 3 5% 4 3 4 3 5% 7% 44%	2823
	11th to 20th	Night	15% 6% 2 5% 4 3 4 3 5% 7% 45%	2823
	21st to end	Night	13% 4 2 5% 3 3 4 3 5% 6% 52%	2979
June	1st to 10th	Night	5% 3 1 4 3 4 4 4 6% 9% 56%	1520
	11th to 20th	Night	6% 4 1 4 3 4 5% 4 7% 8% 55%	1520
	21st to end	Night	4 2 1 4 3 3 4 4 4 9% 61%	1520
July	1st to 10th	Night	11% 5% 2 6% 5% 4 3 4 5% 8% 47%	2848
	11th to 20th	Night	3 2 1 4 3 3 4 4 6% 9% 62%	2850
	21st to end	Night	6% 3 2 4 3 4 4 4 7% 10% 52%	3098
August	1st to 10th	Night	3 2 1 4 3 3 4 4 7% 10% 60%	2836
	11th to 20th	Night	12% 4 2 5% 4 3 4 3 4 6% 53%	2798
	21st to end	Night	6% 4 2 5% 4 3 3 3 5% 8% 58%	3338
September	1st to 10th	Night	10% 4 2 4 3 3 4 3 4 5% 58%	1909
	11th to 20th	Night	9% 4 2 4 4 3 4 3 6% 7% 55%	2090
	21st to end	Night	7% 4 1 4 3 3 3 3 4 6% 60%	2090
October	1st to 10th	Night	12% 5% 2 4 3 2 3 3 4 5% 57%	2255
	11th to 20th	Night	13% 4 2 4 3 3 3 2 3 6% 57%	2280
	21st to end	Night	15% 8% 2 5% 3 3 3 2 3 5% 53%	2508
November	1st to 10th	Night	8% 4 2 3 3 3 3 3 5% 6% 61%	2390
	11th to 20th	Night	11% 5% 2 4 4 3 4 3 4 6% 55%	2665
	21st to end	Night	13% 8% 2 5% 3 3 3 3 4 6% 52%	2800
December	1st to 10th	Night	6% 6% 2 4 3 4 4 3 4 6% 58%	4580
	11th to 20th	Night	11% 7% 3 7% 3 3 4 3 5% 7% 47%	5199
	21st to end	Night	20% 15% 5% 9% 3 3 3 3 3 4 31%	6789

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% 27% 8% 19% 7% 1	4078
	11th to 20th	Day	36% 26% 7% 15% 12% 4	4080
	21st to end	Day	38% 29% 7% 12% 14% 1	4488
February	1st to 10th	Day	21% 62% 7% 6% 3 1	1800
	11th to 20th	Day	19% 61% 5% 8% 7% 1	1763
	21st to end	Day	15% 61% 3 9% 10% 2	1691
March	1st to 10th	Day	25% 29% 6% 15% 20% 6%	4936
	11th to 20th	Day	18% 29% 7% 16% 26% 5%	4980
	21st to end	Day	33% 30% 12% 20% 4 1	5464
April	1st to 10th	Day	17% 62% 5% 8% 6% 1	2293
	11th to 20th	Day	14% 66% 6% 8% 5%	2254
	21st to end	Day	17% 66% 3 9% 4	2465
May	1st to 10th	Day	26% 40% 6% 17% 9% 1	4120
	11th to 20th	Day	28% 41% 8% 14% 10%	4086
	21st to end	Day	20% 40% 5% 23% 11% 1	4583
June	1st to 10th	Day	10% 65% 6% 10% 8% 1	2660
	11th to 20th	Day	11% 65% 6% 11% 5% 1	2660
	21st to end	Day	11% 65% 8% 11% 5%	2655
July	1st to 10th	Day	27% 38% 9% 16% 8% 2	4056
	11th to 20th	Day	16% 37% 7% 27% 11% 1	4051
	21st to end	Day	14% 40% 13% 22% 8% 3	4325
August	1st to 10th	Day	17% 39% 10% 19% 14% 1	4090
	11th to 20th	Day	24% 39% 12% 15% 9% 1	4080
	21st to end	Day	19% 40% 12% 21% 6% 3	4321
September	1st to 10th	Day	10% 60% 6% 12% 9% 2	2268
	11th to 20th	Day	11% 61% 4 13% 8% 2	2090
	21st to end	Day	14% 60% 4 11% 10% 1	2090
October	1st to 10th	Day	10% 36% 3 11% 35% 4	3165
	11th to 20th	Day	6% 36% 2 18% 29% 8%	3140
	21st to end	Day	17% 37% 7% 20% 17% 2	3428
November	1st to 10th	Day	18% 55% 6% 11% 7% 3	1905
	11th to 20th	Day	16% 56% 4 11% 11% 2	1733
	21st to end	Day	19% 56% 5% 12% 8%	1600
December	1st to 10th	Day	16% 37% 9% 25% 13%	2610
	11th to 20th	Day	25% 31% 9% 25% 8%	3005
	21st to end	Day	52% 26% 8% 10% 3 1	4184
January	1st to 10th	Night	43% 28% 8% 14% 6%	5888
	11th to 20th	Night	32% 27% 8% 17% 13% 3	5900
	21st to end	Night	37% 28% 7% 11% 13% 4	6490
February	1st to 10th	Night	19% 62% 6% 8% 5% 1	2600
	11th to 20th	Night	18% 61% 5% 9% 6% 1	2534
	21st to end	Night	13% 62% 3 8% 10% 4	1956
March	1st to 10th	Night	28% 29% 5% 16% 20% 3	4919
	11th to 20th	Night	17% 28% 3 19% 26% 7%	4980
	21st to end	Night	31% 30% 12% 20% 5% 2	5467
April	1st to 10th	Night	16% 63% 5% 8% 7% 1	2105
	11th to 20th	Night	13% 66% 5% 10% 6% 1	1881
	21st to end	Night	15% 65% 3 9% 6% 1	1712
May	1st to 10th	Night	23% 42% 9% 15% 10% 1	2850
	11th to 20th	Night	24% 40% 8% 17% 10%	2824
	21st to end	Night	19% 40% 6% 21% 14%	2987
June	1st to 10th	Night	7% 65% 6% 12% 9% 1	1520
	11th to 20th	Night	10% 66% 4 12% 7% 1	1520
	21st to end	Night	6% 64% 7% 15% 7%	1520
July	1st to 10th	Night	27% 37% 7% 12% 14% 4	2803
	11th to 20th	Night	12% 37% 9% 26% 15%	2796
	21st to end	Night	14% 39% 15% 22% 9%	2999
August	1st to 10th	Night	12% 38% 14% 16% 19% 2	2826
	11th to 20th	Night	23% 38% 9% 17% 12% 1	2825
	21st to end	Night	18% 39% 10% 24% 8% 1	3338
September	1st to 10th	Night	11% 61% 4 11% 9% 3	1909
	11th to 20th	Night	9% 60% 5% 13% 11% 1	2090
	21st to end	Night	13% 59% 4 11% 11% 1	2090
October	1st to 10th	Night	12% 36% 3 10% 36% 4	3762
	11th to 20th	Night	8% 36% 2 20% 24% 9%	3779
	21st to end	Night	20% 37% 4 21% 17% 1	4120
November	1st to 10th	Night	12% 56% 6% 12% 11% 2	2390
	11th to 20th	Night	13% 57% 4 12% 12% 3	2665
	21st to end	Night	18% 57% 5% 12% 9%	2800
December	1st to 10th	Night	15% 36% 10% 25% 14%	4580
	11th to 20th	Night	24% 32% 9% 22% 11% 1	5201
	21st to end	Night	48% 27% 7% 13% 4 1	6789

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% 37% 20% 8%	300
	11th to 20th	Day	20% 19% 41% 17% 3	300
	21st to end	Day	15% 11% 48% 22% 4	330
February	1st to 10th	Day	20% 18% 42% 17% 2 1	300
	11th to 20th	Day	18% 19% 44% 13% 6%	300
	21st to end	Day	13% 20% 45% 18% 5%	249
March	1st to 10th	Day	16% 15% 46% 20% 2	300
	11th to 20th	Day	28% 15% 33% 19% 5% 1	300
	21st to end	Day	32% 18% 33% 13% 3 1	330
April	1st to 10th	Day	24% 16% 36% 18% 6%	393
	11th to 20th	Day	22% 11% 37% 23% 5% 2	452
	21st to end	Day	24% 12% 35% 18% 9% 1	645
May	1st to 10th	Day	20% 11% 38% 21% 7% 2	653
	11th to 20th	Day	19% 9% 28% 29% 13% 2	675
	21st to end	Day	18% 6% 31% 27% 15% 3	734
June	1st to 10th	Day	6% 5% 22% 34% 26% 7%	680
	11th to 20th	Day	7% 4 31% 35% 18% 5%	680
	21st to end	Day	8% 6% 34% 36% 14% 2	680
July	1st to 10th	Day	11% 2 16% 32% 30% 9%	671
	11th to 20th	Day	6% 3 19% 39% 26% 7%	668
	21st to end	Day	10% 2 16% 35% 29% 7%	739
August	1st to 10th	Day	8% 2 15% 39% 29% 6%	676
	11th to 20th	Day	11% 3 18% 38% 24% 7%	665
	21st to end	Day	10% 2 14% 34% 30% 10%	629
September	1st to 10th	Day	13% 2 17% 34% 28% 5%	478
	11th to 20th	Day	7% 4 21% 36% 25% 7%	300
	21st to end	Day	14% 6% 27% 33% 15% 5%	300
October	1st to 10th	Day	13% 6% 28% 27% 20% 6%	300
	11th to 20th	Day	9% 15% 44% 24% 7% 2	300
	21st to end	Day	18% 14% 37% 22% 7% 2	330
November	1st to 10th	Day	16% 9% 39% 25% 8% 2	300
	11th to 20th	Day	16% 15% 39% 21% 8% 1	300
	21st to end	Day	20% 12% 35% 24% 8% 1	300
December	1st to 10th	Day	8% 16% 42% 25% 8% 2	300
	11th to 20th	Day	21% 15% 36% 21% 7% 1	300
	21st to end	Day	23% 19% 37% 18% 2	330
January	1st to 10th	Night	13% 13% 38% 29% 7% 1	1000
	11th to 20th	Night	15% 15% 39% 24% 6% 1	1000
	21st to end	Night	15% 11% 42% 29% 4	1100
February	1st to 10th	Night	17% 13% 42% 25% 3	1000
	11th to 20th	Night	17% 13% 38% 28% 4	979
	21st to end	Night	15% 14% 42% 23% 5% 1	636
March	1st to 10th	Night	15% 13% 43% 25% 5%	600
	11th to 20th	Night	19% 10% 36% 29% 6% 1	600
	21st to end	Night	26% 11% 37% 23% 3	660
April	1st to 10th	Night	14% 12% 41% 26% 6%	600
	11th to 20th	Night	17% 14% 35% 29% 6%	565
	21st to end	Night	20% 8% 38% 27% 7% 1	570
May	1st to 10th	Night	17% 8% 34% 33% 8% 1	570
	11th to 20th	Night	19% 5% 30% 35% 12%	561
	21st to end	Night	13% 6% 27% 39% 13% 2	617
June	1st to 10th	Night	6% 3 23% 43% 25% 1	570
	11th to 20th	Night	8% 3 26% 47% 15% 2	570
	21st to end	Night	4 4 35% 42% 14%	570
July	1st to 10th	Night	8% 1 14% 44% 31% 3	555
	11th to 20th	Night	3 1 16% 50% 28% 2	552
	21st to end	Night	8% 1 13% 47% 29% 2	624
August	1st to 10th	Night	4 1 14% 48% 31% 2	567
	11th to 20th	Night	7% 3 12% 46% 29% 3	564
	21st to end	Night	7% 2 13% 43% 31% 4	627
September	1st to 10th	Night	12% 2 18% 40% 25% 3	570
	11th to 20th	Night	9% 1 21% 42% 24% 2	570
	21st to end	Night	8% 3 26% 44% 18% 2	570
October	1st to 10th	Night	14% 7% 26% 33% 19% 2	735
	11th to 20th	Night	15% 8% 39% 30% 8% 1	760
	21st to end	Night	18% 10% 35% 27% 9%	836
November	1st to 10th	Night	9% 11% 32% 37% 10% 1	830
	11th to 20th	Night	14% 12% 38% 29% 7%	1000
	21st to end	Night	16% 11% 37% 28% 8%	1000
December	1st to 10th	Night	13% 12% 35% 32% 7% 1	1000
	11th to 20th	Night	18% 9% 40% 27% 6%	1000
	21st to end	Night	19% 14% 36% 27% 4	1100

Page generated at 2025-04-08 08:17:28. Version ac07

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