Topeka
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Topeka clear sky chart from 2005-11-06 to 2025-04-26.

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	10% 7% 3 6% 4 4 4 3 5% 7% 47%	113608
	Night	10% 7% 2 6% 4 4 4 3 5% 6% 50%	115158
Transparency	Day	37% 2 11% 27% 19% 4	117273
	Night	36% 2 10% 27% 21% 4	119622
Seeing	Day	15% 10% 31% 28% 14% 3	16213
	Night	14% 9% 33% 33% 11% 1	26236

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% 3 10% 4 4 3 3 5% 6% 38%	4077
	11th to 20th	Day	7% 8% 4 10% 6% 6% 4 3 4 6% 40%	4080
	21st to end	Day	11% 13% 5% 6% 4 4 3 3 4 5% 42%	4488
February	1st to 10th	Day	13% 11% 4 7% 5% 5% 3 3 4 6% 40%	1800
	11th to 20th	Day	9% 11% 3 7% 4 4 4 3 6% 6% 42%	1804
	21st to end	Day	9% 9% 3 6% 4 3 4 3 6% 5% 48%	1667
March	1st to 10th	Day	12% 7% 2 6% 3 3 3 2 4 6% 53%	4936
	11th to 20th	Day	10% 6% 1 4 3 3 3 3 5% 6% 55%	4980
	21st to end	Day	12% 9% 5% 7% 4 4 5% 4 5% 6% 38%	5462
April	1st to 10th	Day	14% 7% 2 6% 3 2 3 3 5% 7% 48%	2259
	11th to 20th	Day	13% 7% 3 7% 4 4 5% 4 5% 6% 42%	2398
	21st to end	Day	18% 8% 3 7% 4 4 4 3 5% 6% 39%	2536
May	1st to 10th	Day	14% 10% 3 7% 4 4 4 3 5% 6% 40%	4082
	11th to 20th	Day	16% 7% 2 6% 4 4 4 4 5% 7% 40%	4082
	21st to end	Day	13% 7% 2 6% 4 4 4 4 6% 7% 44%	4477
June	1st to 10th	Day	5% 4 1 5% 4 4 4 5% 8% 11% 49%	2481
	11th to 20th	Day	7% 5% 2 5% 4 4 5% 4 5% 8% 49%	2594
	21st to end	Day	6% 4 2 5% 4 4 4 4 6% 9% 52%	2470
July	1st to 10th	Day	11% 6% 2 6% 4 4 5% 4 6% 8% 43%	4120
	11th to 20th	Day	5% 4 1 4 4 4 4 5% 7% 10% 52%	4120
	21st to end	Day	5% 4 2 5% 4 4 5% 4 8% 10% 48%	4465
August	1st to 10th	Day	6% 5% 2 4 3 4 5% 4 6% 8% 53%	4104
	11th to 20th	Day	12% 5% 2 6% 4 4 4 3 5% 8% 47%	4041
	21st to end	Day	5% 3 1 5% 4 4 4 4 6% 8% 55%	4354
September	1st to 10th	Day	11% 4 1 5% 4 3 3 2 5% 7% 54%	2214
	11th to 20th	Day	9% 5% 2 6% 5% 4 5% 4 5% 7% 49%	2090
	21st to end	Day	8% 5% 1 5% 3 3 5% 3 5% 7% 55%	2090
October	1st to 10th	Day	10% 5% 2 6% 2 3 3 3 5% 8% 52%	1933
	11th to 20th	Day	10% 6% 2 4 3 2 3 3 4 4 59%	1900
	21st to end	Day	15% 5% 2 5% 3 3 3 3 4 5% 51%	2090
November	1st to 10th	Day	9% 5% 2 4 4 3 3 4 4 6% 55%	1883
	11th to 20th	Day	11% 6% 2 5% 3 3 3 3 4 4 57%	1800
	21st to end	Day	15% 7% 2 5% 3 2 3 3 5% 5% 51%	1648
December	1st to 10th	Day	6% 5% 2 4 3 3 3 3 5% 7% 58%	2610
	11th to 20th	Day	9% 8% 3 6% 4 4 4 3 4 5% 51%	3008
	21st to end	Day	18% 14% 7% 11% 4 4 3 3 4 5% 27%	4465
January	1st to 10th	Night	12% 9% 4 14% 5% 4 4 3 4 5% 36%	5888
	11th to 20th	Night	7% 8% 3 8% 5% 5% 5% 3 4 6% 46%	5900
	21st to end	Night	13% 9% 4 7% 4 3 3 3 4 5% 43%	6490
February	1st to 10th	Night	11% 12% 3 7% 5% 4 4 3 6% 6% 40%	2600
	11th to 20th	Night	10% 8% 3 8% 5% 4 4 2 5% 6% 45%	2499
	21st to end	Night	10% 7% 2 6% 4 4 4 3 4 5% 51%	1961
March	1st to 10th	Night	13% 7% 2 4 3 3 2 2 3 4 55%	4919
	11th to 20th	Night	8% 5% 1 3 3 3 3 3 6% 8% 57%	4980
	21st to end	Night	14% 8% 3 6% 4 4 4 4 6% 7% 41%	5467
April	1st to 10th	Night	11% 6% 2 5% 4 4 3 2 5% 6% 51%	2140
	11th to 20th	Night	12% 7% 3 5% 4 3 4 3 5% 7% 46%	1946
	21st to end	Night	16% 6% 3 5% 4 5% 4 3 5% 6% 43%	1760
May	1st to 10th	Night	15% 8% 2 6% 4 4 4 3 5% 7% 42%	2823
	11th to 20th	Night	15% 6% 3 5% 4 4 4 3 5% 8% 44%	2823
	21st to end	Night	11% 5% 1 5% 3 3 4 3 6% 8% 53%	3090
June	1st to 10th	Night	5% 3 2 5% 3 4 3 3 6% 9% 57%	1677
	11th to 20th	Night	6% 3 2 4 3 4 5% 4 7% 8% 54%	1563
	21st to end	Night	4 3 1 4 3 3 4 3 6% 10% 60%	1710
July	1st to 10th	Night	10% 6% 2 6% 4 4 3 4 5% 6% 51%	2850
	11th to 20th	Night	2 2 1 4 3 4 4 4 6% 9% 60%	2850
	21st to end	Night	5% 3 2 6% 4 4 4 4 7% 11% 51%	3098
August	1st to 10th	Night	2 2 1 4 4 5% 4 4 7% 10% 58%	2836
	11th to 20th	Night	9% 5% 3 5% 4 4 4 3 5% 8% 50%	2798
	21st to end	Night	5% 3 2 5% 3 3 3 3 5% 8% 59%	3307
September	1st to 10th	Night	10% 4 1 5% 3 3 3 3 5% 6% 56%	1962
	11th to 20th	Night	8% 4 1 5% 3 3 5% 3 5% 7% 55%	2090
	21st to end	Night	6% 4 2 5% 4 3 3 3 4 6% 60%	2090
October	1st to 10th	Night	11% 4 2 5% 3 3 3 3 5% 7% 55%	2227
	11th to 20th	Night	12% 4 2 3 3 3 3 2 3 6% 59%	2280
	21st to end	Night	14% 6% 2 5% 3 3 3 2 3 5% 54%	2508
November	1st to 10th	Night	9% 5% 2 4 3 3 3 3 4 5% 61%	2410
	11th to 20th	Night	9% 6% 1 4 3 4 4 3 4 6% 56%	2600
	21st to end	Night	12% 6% 2 3 3 3 3 2 4 6% 54%	2746
December	1st to 10th	Night	6% 6% 2 5% 3 4 3 3 5% 6% 58%	4580
	11th to 20th	Night	10% 7% 3 6% 4 4 4 4 5% 6% 48%	5199
	21st to end	Night	19% 14% 5% 8% 4 3 4 3 4 4 34%	6491

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	49% 2 10% 27% 12% 1	4078
	11th to 20th	Day	48% 1 10% 21% 17% 3	4080
	21st to end	Day	46% 2 11% 21% 18% 2	4488
February	1st to 10th	Day	48% 3 12% 24% 11% 3	1800
	11th to 20th	Day	44% 2 12% 25% 14% 3	1813
	21st to end	Day	38% 2 9% 28% 19% 5%	1667
March	1st to 10th	Day	35% 1 9% 21% 24% 10%	4936
	11th to 20th	Day	32% 1 8% 22% 28% 9%	4980
	21st to end	Day	47% 2 13% 30% 7% 1	5464
April	1st to 10th	Day	38% 2 11% 24% 21% 3	2259
	11th to 20th	Day	42% 3 11% 24% 18% 1	2398
	21st to end	Day	47% 3 10% 27% 12% 1	2536
May	1st to 10th	Day	46% 3 9% 25% 15% 2	4120
	11th to 20th	Day	44% 2 13% 24% 17%	4086
	21st to end	Day	40% 3 9% 32% 14% 2	4489
June	1st to 10th	Day	28% 4 17% 32% 18% 2	2481
	11th to 20th	Day	32% 4 13% 30% 19% 2	2594
	21st to end	Day	29% 3 14% 31% 18% 4	2470
July	1st to 10th	Day	39% 3 12% 23% 19% 4	4056
	11th to 20th	Day	27% 3 11% 35% 21% 3	4051
	21st to end	Day	30% 2 15% 33% 17% 3	4325
August	1st to 10th	Day	30% 3 12% 27% 24% 4	4090
	11th to 20th	Day	38% 2 15% 26% 17% 1	4080
	21st to end	Day	28% 2 16% 31% 18% 6%	4353
September	1st to 10th	Day	31% 3 11% 28% 20% 7%	2214
	11th to 20th	Day	35% 3 9% 27% 23% 3	2090
	21st to end	Day	30% 3 9% 30% 25% 3	2090
October	1st to 10th	Day	21% 1 6% 22% 42% 8%	3206
	11th to 20th	Day	19% 1 4 30% 34% 11%	3140
	21st to end	Day	31% 1 9% 28% 26% 5%	3428
November	1st to 10th	Day	30% 3 12% 30% 20% 6%	1883
	11th to 20th	Day	33% 1 9% 29% 24% 4	1800
	21st to end	Day	37% 2 9% 28% 22% 2	1648
December	1st to 10th	Day	27% 2 11% 41% 18% 1	2610
	11th to 20th	Day	38% 1 11% 35% 14% 1	3005
	21st to end	Day	62% 1 9% 20% 7% 1	4465
January	1st to 10th	Night	52% 1 10% 24% 12% 1	5888
	11th to 20th	Night	41% 2 9% 24% 20% 3	5900
	21st to end	Night	45% 1 10% 19% 19% 6%	6490
February	1st to 10th	Night	45% 3 11% 24% 14% 3	2600
	11th to 20th	Night	42% 2 11% 26% 16% 3	2500
	21st to end	Night	36% 2 8% 24% 22% 7%	1961
March	1st to 10th	Night	36% 1 5% 26% 27% 5%	4919
	11th to 20th	Night	27% 1 7% 22% 34% 10%	4980
	21st to end	Night	44% 2 14% 28% 9% 2	5467
April	1st to 10th	Night	35% 2 11% 25% 23% 5%	2140
	11th to 20th	Night	38% 3 8% 28% 19% 4	1946
	21st to end	Night	43% 3 10% 27% 15% 2	1760
May	1st to 10th	Night	42% 3 13% 24% 15% 3	2850
	11th to 20th	Night	41% 2 13% 27% 17% 1	2824
	21st to end	Night	31% 3 14% 32% 18% 1	3099
June	1st to 10th	Night	25% 3 19% 34% 16% 3	1677
	11th to 20th	Night	26% 4 14% 34% 18% 3	1563
	21st to end	Night	22% 2 14% 36% 22% 4	1710
July	1st to 10th	Night	36% 1 12% 24% 21% 5%	2805
	11th to 20th	Night	20% 3 12% 36% 26% 3	2796
	21st to end	Night	29% 2 16% 32% 19% 1	2999
August	1st to 10th	Night	22% 2 19% 28% 22% 7%	2826
	11th to 20th	Night	34% 2 15% 27% 20% 2	2825
	21st to end	Night	25% 2 13% 36% 19% 5%	3307
September	1st to 10th	Night	30% 2 9% 29% 21% 9%	1962
	11th to 20th	Night	29% 3 9% 28% 26% 5%	2090
	21st to end	Night	27% 2 8% 27% 32% 4	2090
October	1st to 10th	Night	21% 2 5% 18% 46% 7%	3721
	11th to 20th	Night	21% 1 4 30% 31% 13%	3779
	21st to end	Night	32% 1 6% 30% 28% 3	4120
November	1st to 10th	Night	28% 2 11% 28% 24% 7%	2410
	11th to 20th	Night	30% 2 9% 29% 25% 5%	2600
	21st to end	Night	34% 2 10% 31% 21% 3	2746
December	1st to 10th	Night	28% 2 13% 35% 20% 1	4580
	11th to 20th	Night	39% 1 10% 31% 16% 3	5201
	21st to end	Night	56% 2 8% 25% 8% 1	6491

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% 15% 35% 21% 6%	300
	11th to 20th	Day	22% 19% 41% 16% 3	300
	21st to end	Day	13% 15% 47% 22% 3	330
February	1st to 10th	Day	22% 22% 37% 18% 2	300
	11th to 20th	Day	20% 21% 43% 11% 6%	300
	21st to end	Day	14% 26% 45% 12% 4	249
March	1st to 10th	Day	18% 18% 43% 19% 2	300
	11th to 20th	Day	26% 13% 39% 18% 5%	300
	21st to end	Day	29% 20% 40% 9% 3	330
April	1st to 10th	Day	26% 18% 33% 19% 4	359
	11th to 20th	Day	21% 16% 38% 20% 5%	516
	21st to end	Day	25% 14% 34% 18% 8%	676
May	1st to 10th	Day	22% 12% 37% 21% 8% 1	653
	11th to 20th	Day	20% 9% 30% 27% 13% 2	675
	21st to end	Day	18% 10% 31% 27% 13% 2	734
June	1st to 10th	Day	6% 4 25% 37% 23% 6%	680
	11th to 20th	Day	8% 5% 32% 34% 17% 4	680
	21st to end	Day	9% 6% 35% 36% 12% 1	680
July	1st to 10th	Day	11% 2 18% 34% 26% 8%	671
	11th to 20th	Day	5% 2 22% 38% 27% 7%	668
	21st to end	Day	9% 2 20% 35% 28% 6%	739
August	1st to 10th	Day	9% 3 19% 38% 26% 5%	676
	11th to 20th	Day	10% 2 20% 43% 21% 4	665
	21st to end	Day	9% 2 17% 37% 28% 7%	648
September	1st to 10th	Day	13% 1 22% 38% 22% 4	424
	11th to 20th	Day	6% 3 27% 38% 22% 3	300
	21st to end	Day	16% 5% 30% 35% 12% 3	300
October	1st to 10th	Day	14% 9% 29% 27% 16% 5%	300
	11th to 20th	Day	11% 19% 42% 20% 8%	300
	21st to end	Day	22% 15% 35% 21% 7% 1	330
November	1st to 10th	Day	17% 14% 37% 24% 5% 2	300
	11th to 20th	Day	17% 17% 39% 21% 6%	300
	21st to end	Day	23% 13% 38% 17% 9%	300
December	1st to 10th	Day	10% 15% 42% 25% 5% 2	300
	11th to 20th	Day	19% 17% 38% 19% 6% 1	300
	21st to end	Day	23% 22% 33% 20% 2	330
January	1st to 10th	Night	13% 14% 37% 30% 7%	1000
	11th to 20th	Night	16% 13% 38% 28% 5% 1	1000
	21st to end	Night	15% 13% 39% 29% 4	1100
February	1st to 10th	Night	18% 14% 39% 26% 3	1000
	11th to 20th	Night	16% 15% 38% 28% 3	945
	21st to end	Night	15% 14% 41% 25% 5%	641
March	1st to 10th	Night	14% 15% 40% 25% 6%	600
	11th to 20th	Night	19% 12% 37% 26% 5% 1	600
	21st to end	Night	25% 11% 38% 22% 4	660
April	1st to 10th	Night	16% 13% 40% 26% 6%	600
	11th to 20th	Night	17% 15% 40% 24% 5%	593
	21st to end	Night	22% 10% 38% 23% 6% 1	587
May	1st to 10th	Night	19% 8% 37% 29% 6%	570
	11th to 20th	Night	16% 6% 32% 34% 11% 1	561
	21st to end	Night	12% 7% 31% 34% 14% 2	617
June	1st to 10th	Night	7% 2 26% 41% 22% 1	570
	11th to 20th	Night	7% 3 32% 41% 16% 1	570
	21st to end	Night	7% 4 34% 42% 12% 1	570
July	1st to 10th	Night	10% 1 15% 47% 24% 2	555
	11th to 20th	Night	4 1 21% 51% 22% 3	552
	21st to end	Night	8% 1 17% 46% 26% 2	624
August	1st to 10th	Night	4 1 19% 47% 27% 2	567
	11th to 20th	Night	8% 1 15% 51% 24% 2	564
	21st to end	Night	7% 1 19% 42% 28% 2	627
September	1st to 10th	Night	13% 2 20% 44% 19% 2	570
	11th to 20th	Night	10% 1 26% 41% 20% 3	570
	21st to end	Night	7% 4 28% 42% 18% 1	570
October	1st to 10th	Night	14% 5% 29% 34% 17% 1	707
	11th to 20th	Night	15% 9% 41% 28% 8%	760
	21st to end	Night	20% 12% 34% 26% 8%	836
November	1st to 10th	Night	12% 10% 32% 35% 10% 1	850
	11th to 20th	Night	12% 14% 37% 28% 7%	1000
	21st to end	Night	17% 11% 34% 30% 8%	1000
December	1st to 10th	Night	14% 12% 36% 31% 6% 1	1000
	11th to 20th	Night	18% 11% 38% 28% 5%	1000
	21st to end	Night	20% 13% 35% 27% 4	1100

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