Ottawa (KS)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ottawa (KS) clear sky chart from 2005-11-06 to 2025-07-21.

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%	119889
	Night	11% 6% 2 6% 4 4 4 3 5% 6% 49%	119427
Transparency	Day	36% 6% 11% 26% 18% 4	123542
	Night	34% 5% 11% 26% 20% 4	123904
Seeing	Day	14% 10% 29% 28% 16% 4	16614
	Night	14% 9% 32% 33% 12% 1	26454

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	16% 9% 3 9% 4 5% 3 3 4 6% 38%	4077
	11th to 20th	Day	7% 8% 4 9% 6% 6% 5% 3 4 5% 42%	4080
	21st to end	Day	12% 12% 4 7% 5% 4 4 3 4 5% 41%	4488
February	1st to 10th	Day	14% 12% 4 6% 4 4 3 2 3 6% 41%	1800
	11th to 20th	Day	12% 9% 3 8% 5% 5% 4 2 4 6% 42%	1784
	21st to end	Day	11% 7% 3 7% 3 4 4 4 5% 6% 46%	1695
March	1st to 10th	Day	11% 8% 2 5% 3 3 3 3 4 6% 52%	4936
	11th to 20th	Day	9% 6% 2 4 3 2 3 3 5% 6% 57%	4980
	21st to end	Day	11% 10% 4 8% 5% 5% 4 3 6% 7% 37%	5462
April	1st to 10th	Day	14% 7% 2 6% 4 3 4 2 4 6% 46%	2275
	11th to 20th	Day	15% 7% 3 6% 4 4 4 3 5% 6% 42%	2374
	21st to end	Day	19% 8% 2 7% 5% 4 5% 4 4 6% 37%	2579
May	1st to 10th	Day	16% 8% 2 6% 4 4 4 3 4 6% 43%	5862
	11th to 20th	Day	13% 6% 2 6% 4 3 4 3 6% 8% 46%	5862
	21st to end	Day	19% 6% 2 6% 4 3 4 4 5% 8% 40%	6434
June	1st to 10th	Day	7% 3 2 4 4 5% 4 5% 8% 11% 47%	2660
	11th to 20th	Day	7% 5% 2 5% 4 4 4 3 7% 9% 48%	2774
	21st to end	Day	6% 4 2 5% 4 4 4 4 6% 9% 52%	2600
July	1st to 10th	Day	11% 6% 2 6% 4 4 5% 4 7% 8% 43%	4250
	11th to 20th	Day	5% 4 2 5% 3 4 4 4 7% 10% 53%	4250
	21st to end	Day	6% 4 2 5% 4 5% 6% 5% 9% 11% 43%	4466
August	1st to 10th	Day	6% 4 2 5% 4 4 4 4 5% 8% 54%	4104
	11th to 20th	Day	11% 6% 2 6% 4 4 4 4 5% 8% 47%	4041
	21st to end	Day	6% 4 1 5% 3 3 4 4 6% 8% 56%	4313
September	1st to 10th	Day	13% 5% 2 5% 3 3 2 3 5% 7% 54%	2242
	11th to 20th	Day	9% 5% 2 5% 4 3 5% 4 5% 8% 50%	2090
	21st to end	Day	9% 4 2 5% 4 3 4 4 5% 6% 54%	2090
October	1st to 10th	Day	11% 6% 2 5% 3 4 3 3 5% 6% 53%	1916
	11th to 20th	Day	11% 6% 1 4 2 3 2 2 4 5% 59%	1900
	21st to end	Day	15% 6% 2 6% 3 4 3 2 3 5% 51%	2090
November	1st to 10th	Day	10% 7% 1 5% 3 2 4 3 4 5% 56%	1929
	11th to 20th	Day	13% 6% 2 4 2 3 3 3 4 7% 53%	1800
	21st to end	Day	14% 8% 3 5% 4 2 2 2 4 5% 51%	1627
December	1st to 10th	Day	6% 6% 2 4 3 4 3 3 4 7% 57%	2610
	11th to 20th	Day	10% 7% 3 6% 4 4 4 3 4 5% 51%	3008
	21st to end	Day	19% 16% 7% 8% 4 4 4 3 4 5% 26%	4441
January	1st to 10th	Night	12% 9% 4 12% 4 5% 4 3 4 5% 37%	5888
	11th to 20th	Night	8% 7% 3 8% 5% 6% 5% 3 5% 6% 44%	5900
	21st to end	Night	14% 9% 3 7% 4 4 3 3 4 6% 43%	6490
February	1st to 10th	Night	11% 11% 3 6% 5% 4 4 4 5% 5% 41%	2600
	11th to 20th	Night	12% 10% 3 6% 4 3 3 3 5% 6% 44%	2518
	21st to end	Night	12% 5% 3 7% 4 3 4 4 5% 5% 49%	1933
March	1st to 10th	Night	14% 7% 3 4 3 2 2 3 3 5% 53%	4919
	11th to 20th	Night	7% 4 1 4 3 3 3 3 6% 7% 58%	4980
	21st to end	Night	13% 8% 2 7% 4 4 4 4 5% 7% 41%	5467
April	1st to 10th	Night	10% 6% 2 6% 3 3 5% 3 5% 6% 50%	2124
	11th to 20th	Night	14% 7% 3 5% 3 3 4 3 5% 6% 48%	1975
	21st to end	Night	17% 6% 2 6% 4 4 3 3 5% 6% 42%	1818
May	1st to 10th	Night	16% 7% 2 5% 4 3 4 3 4 7% 45%	4053
	11th to 20th	Night	14% 6% 2 5% 3 3 3 2 4 6% 52%	4053
	21st to end	Night	18% 5% 2 3 3 2 3 3 4 6% 51%	4443
June	1st to 10th	Night	5% 3 1 4 4 4 5% 5% 6% 10% 53%	1725
	11th to 20th	Night	4 4 2 5% 3 4 4 4 7% 10% 52%	1608
	21st to end	Night	5% 3 1 4 2 4 4 3 6% 9% 59%	1800
July	1st to 10th	Night	9% 7% 2 6% 4 3 4 3 5% 6% 51%	2940
	11th to 20th	Night	2 3 2 4 3 3 4 3 6% 10% 60%	2940
	21st to end	Night	7% 3 2 5% 4 4 5% 4 9% 10% 45%	3098
August	1st to 10th	Night	2 2 1 3 4 4 4 5% 6% 10% 58%	2836
	11th to 20th	Night	8% 6% 2 6% 4 4 4 3 5% 8% 50%	2798
	21st to end	Night	3 3 2 6% 4 3 4 3 5% 7% 60%	3347
September	1st to 10th	Night	10% 4 2 4 3 4 4 3 3 5% 57%	1933
	11th to 20th	Night	9% 4 1 5% 3 3 4 3 5% 8% 54%	2090
	21st to end	Night	6% 4 2 4 4 3 4 3 4 6% 59%	2090
October	1st to 10th	Night	11% 3 2 3 3 3 3 3 4 7% 57%	2243
	11th to 20th	Night	12% 5% 1 4 3 2 3 2 3 5% 59%	2280
	21st to end	Night	14% 7% 3 5% 3 2 3 2 4 5% 53%	2508
November	1st to 10th	Night	10% 4 2 4 3 3 3 2 4 5% 60%	2365
	11th to 20th	Night	10% 7% 2 4 3 3 3 2 5% 7% 55%	2600
	21st to end	Night	15% 6% 2 4 3 2 3 2 4 5% 54%	2768
December	1st to 10th	Night	6% 6% 1 4 3 3 3 3 5% 6% 59%	4580
	11th to 20th	Night	12% 6% 3 6% 3 3 4 4 6% 6% 47%	5199
	21st to end	Night	19% 14% 4 8% 4 4 4 2 4 4 32%	6518

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	47% 5% 10% 24% 12% 1	4078
	11th to 20th	Day	45% 3 11% 22% 17% 3	4080
	21st to end	Day	46% 4 10% 20% 16% 5%	4488
February	1st to 10th	Day	47% 4 11% 25% 10% 3	1800
	11th to 20th	Day	44% 5% 11% 23% 14% 3	1793
	21st to end	Day	38% 5% 11% 24% 18% 5%	1695
March	1st to 10th	Day	35% 4 8% 21% 23% 10%	4936
	11th to 20th	Day	28% 4 10% 22% 27% 10%	4980
	21st to end	Day	45% 6% 12% 28% 7% 1	5464
April	1st to 10th	Day	39% 5% 11% 23% 18% 3	2275
	11th to 20th	Day	42% 6% 12% 23% 17% 1	2374
	21st to end	Day	48% 6% 11% 23% 11% 1	2579
May	1st to 10th	Day	42% 7% 9% 23% 18% 1	5900
	11th to 20th	Day	35% 7% 10% 24% 20% 4	5866
	21st to end	Day	42% 7% 11% 25% 14% 1	6447
June	1st to 10th	Day	27% 10% 17% 27% 17% 2	2660
	11th to 20th	Day	31% 7% 13% 29% 18% 2	2774
	21st to end	Day	27% 8% 15% 29% 18% 3	2600
July	1st to 10th	Day	37% 7% 12% 22% 19% 3	4186
	11th to 20th	Day	26% 7% 12% 35% 18% 3	4181
	21st to end	Day	29% 10% 17% 29% 14% 2	4326
August	1st to 10th	Day	28% 7% 12% 27% 22% 4	4090
	11th to 20th	Day	35% 6% 16% 26% 15% 2	4080
	21st to end	Day	25% 6% 14% 34% 16% 4	4312
September	1st to 10th	Day	31% 4 12% 26% 19% 7%	2242
	11th to 20th	Day	31% 6% 11% 27% 23% 2	2090
	21st to end	Day	30% 5% 10% 25% 26% 4	2090
October	1st to 10th	Day	19% 3 7% 22% 40% 9%	3176
	11th to 20th	Day	18% 2 5% 29% 35% 11%	3140
	21st to end	Day	30% 3 10% 26% 27% 4	3428
November	1st to 10th	Day	30% 5% 12% 29% 19% 5%	1929
	11th to 20th	Day	32% 4 9% 27% 23% 5%	1800
	21st to end	Day	38% 3 8% 28% 21% 2	1627
December	1st to 10th	Day	28% 4 10% 39% 18% 1	2610
	11th to 20th	Day	37% 4 9% 33% 16% 1	3005
	21st to end	Day	60% 5% 10% 18% 7% 1	4441
January	1st to 10th	Night	49% 5% 11% 22% 11% 1	5888
	11th to 20th	Night	40% 5% 9% 24% 18% 3	5900
	21st to end	Night	42% 4 11% 19% 17% 6%	6490
February	1st to 10th	Night	44% 6% 11% 22% 15% 3	2600
	11th to 20th	Night	41% 5% 11% 23% 16% 3	2519
	21st to end	Night	36% 5% 8% 23% 21% 8%	1933
March	1st to 10th	Night	34% 4 6% 25% 26% 5%	4919
	11th to 20th	Night	25% 4 8% 20% 34% 9%	4980
	21st to end	Night	40% 7% 15% 24% 11% 2	5467
April	1st to 10th	Night	35% 5% 11% 22% 22% 5%	2124
	11th to 20th	Night	37% 6% 9% 25% 19% 4	1975
	21st to end	Night	41% 6% 13% 24% 14% 2	1818
May	1st to 10th	Night	38% 9% 12% 24% 16% 2	4080
	11th to 20th	Night	34% 6% 10% 26% 18% 7%	4054
	21st to end	Night	35% 6% 10% 28% 20% 1	4452
June	1st to 10th	Night	24% 9% 18% 30% 16% 3	1725
	11th to 20th	Night	25% 7% 15% 31% 19% 2	1608
	21st to end	Night	21% 7% 13% 34% 22% 4	1800
July	1st to 10th	Night	34% 7% 11% 23% 20% 5%	2895
	11th to 20th	Night	20% 6% 14% 36% 22% 3	2886
	21st to end	Night	29% 8% 19% 30% 14% 1	2999
August	1st to 10th	Night	20% 7% 18% 28% 20% 7%	2826
	11th to 20th	Night	31% 6% 14% 26% 20% 2	2825
	21st to end	Night	24% 4 12% 38% 17% 4	3347
September	1st to 10th	Night	28% 7% 9% 26% 21% 9%	1933
	11th to 20th	Night	28% 6% 11% 26% 24% 4	2090
	21st to end	Night	26% 5% 8% 25% 30% 5%	2090
October	1st to 10th	Night	18% 4 6% 18% 47% 8%	3750
	11th to 20th	Night	21% 3 5% 26% 32% 14%	3779
	21st to end	Night	30% 4 8% 29% 26% 4	4120
November	1st to 10th	Night	27% 4 11% 27% 24% 6%	2365
	11th to 20th	Night	31% 4 9% 26% 25% 5%	2600
	21st to end	Night	34% 3 10% 29% 20% 4	2768
December	1st to 10th	Night	26% 5% 14% 34% 19% 1	4580
	11th to 20th	Night	36% 5% 11% 28% 18% 3	5201
	21st to end	Night	55% 5% 8% 22% 7% 1	6518

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% 34% 22% 8%	300
	11th to 20th	Day	22% 15% 42% 18% 3	300
	21st to end	Day	12% 12% 50% 23% 3 1	330
February	1st to 10th	Day	24% 18% 35% 19% 2 1	300
	11th to 20th	Day	19% 19% 43% 15% 5%	300
	21st to end	Day	12% 27% 43% 14% 4	249
March	1st to 10th	Day	18% 18% 39% 22% 3	300
	11th to 20th	Day	24% 15% 34% 20% 6%	300
	21st to end	Day	26% 23% 34% 14% 2 1	330
April	1st to 10th	Day	22% 19% 34% 18% 7%	375
	11th to 20th	Day	21% 17% 37% 19% 5%	492
	21st to end	Day	22% 14% 37% 20% 7% 1	679
May	1st to 10th	Day	19% 14% 35% 22% 9% 1	703
	11th to 20th	Day	19% 12% 29% 25% 14% 2	725
	21st to end	Day	18% 10% 28% 24% 15% 5%	789
June	1st to 10th	Day	7% 4 22% 35% 25% 8%	730
	11th to 20th	Day	8% 3 29% 36% 20% 4	730
	21st to end	Day	7% 5% 34% 35% 17% 2	730
July	1st to 10th	Day	11% 3 14% 33% 28% 12%	721
	11th to 20th	Day	5% 2 19% 37% 30% 8%	718
	21st to end	Day	9% 2 15% 37% 29% 7%	740
August	1st to 10th	Day	9% 2 14% 38% 30% 6%	676
	11th to 20th	Day	8% 2 18% 37% 29% 5%	665
	21st to end	Day	9% 1 15% 30% 35% 10%	620
September	1st to 10th	Day	13% 2 12% 37% 30% 6%	452
	11th to 20th	Day	5% 3 18% 40% 29% 6%	300
	21st to end	Day	14% 5% 23% 38% 16% 4	300
October	1st to 10th	Day	12% 8% 29% 26% 18% 8%	300
	11th to 20th	Day	8% 16% 40% 26% 9% 1	300
	21st to end	Day	21% 13% 39% 20% 5% 2	330
November	1st to 10th	Day	19% 11% 33% 27% 8% 3	300
	11th to 20th	Day	21% 17% 29% 24% 9% 1	300
	21st to end	Day	22% 13% 36% 21% 8%	300
December	1st to 10th	Day	9% 16% 39% 27% 6% 3	300
	11th to 20th	Day	18% 14% 38% 24% 6% 1	300
	21st to end	Day	24% 19% 37% 17% 2	330
January	1st to 10th	Night	13% 12% 40% 30% 6%	1000
	11th to 20th	Night	14% 14% 39% 27% 6% 1	1000
	21st to end	Night	13% 14% 41% 29% 3	1100
February	1st to 10th	Night	17% 13% 41% 25% 3	1000
	11th to 20th	Night	18% 14% 38% 27% 3	964
	21st to end	Night	17% 13% 40% 26% 4	613
March	1st to 10th	Night	14% 13% 43% 27% 4	600
	11th to 20th	Night	18% 12% 39% 26% 6%	600
	21st to end	Night	23% 14% 35% 23% 4	660
April	1st to 10th	Night	14% 13% 41% 26% 6%	600
	11th to 20th	Night	17% 16% 35% 27% 5%	593
	21st to end	Night	19% 12% 35% 28% 7% 1	600
May	1st to 10th	Night	18% 7% 34% 33% 7% 1	600
	11th to 20th	Night	15% 7% 30% 34% 14%	591
	21st to end	Night	14% 5% 29% 34% 16% 2	650
June	1st to 10th	Night	6% 4 21% 44% 24% 1	600
	11th to 20th	Night	6% 4 27% 43% 19% 1	600
	21st to end	Night	5% 3 33% 45% 15%	600
July	1st to 10th	Night	9% 2 14% 44% 30% 2	585
	11th to 20th	Night	3 1 17% 50% 26% 3	582
	21st to end	Night	7% 2 13% 46% 30% 2	624
August	1st to 10th	Night	6% 1 15% 47% 30% 2	567
	11th to 20th	Night	7% 2 13% 45% 31% 2	564
	21st to end	Night	6% 1 13% 43% 35% 2	627
September	1st to 10th	Night	11% 1 18% 45% 23% 2	570
	11th to 20th	Night	10% 2 22% 40% 22% 4	570
	21st to end	Night	8% 4 23% 42% 21% 2	570
October	1st to 10th	Night	12% 4 28% 35% 19% 2	723
	11th to 20th	Night	16% 7% 39% 30% 8%	760
	21st to end	Night	17% 12% 33% 28% 9%	836
November	1st to 10th	Night	12% 10% 34% 33% 11% 1	805
	11th to 20th	Night	14% 13% 35% 30% 7%	1000
	21st to end	Night	18% 11% 34% 31% 6%	1000
December	1st to 10th	Night	15% 11% 36% 31% 6% 1	1000
	11th to 20th	Night	19% 11% 37% 28% 5%	1000
	21st to end	Night	20% 14% 35% 27% 4	1100

Page generated at 2025-07-18 00:10:01. Version ac07

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