Owatonna
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Owatonna clear sky chart from 2005-11-06 to 2026-01-17.

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% 9% 3 8% 5% 4 4 4 6% 7% 37%	127829
	Night	12% 9% 4 9% 5% 4 4 4 5% 6% 38%	124141
Transparency	Day	46% 3 13% 25% 12% 1	131407
	Night	46% 3 12% 24% 13% 2	128639
Seeing	Day	17% 10% 31% 27% 13% 3	17594
	Night	16% 9% 34% 30% 10% 1	27557

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	6% 14% 6% 19% 11% 8% 6% 4 4 5% 16%	3697
	11th to 20th	Day	6% 12% 5% 12% 8% 7% 8% 7% 12% 7% 15%	3788
	21st to end	Day	7% 14% 9% 15% 7% 5% 6% 3 4 5% 26%	4488
February	1st to 10th	Day	8% 12% 6% 12% 8% 7% 6% 6% 6% 6% 24%	1800
	11th to 20th	Day	9% 11% 5% 9% 6% 6% 7% 5% 6% 6% 30%	1754
	21st to end	Day	13% 9% 4 9% 7% 5% 5% 4 6% 7% 30%	1560
March	1st to 10th	Day	13% 7% 3 6% 4 3 4 3 5% 7% 44%	4847
	11th to 20th	Day	11% 9% 3 6% 3 3 4 4 5% 9% 43%	4980
	21st to end	Day	23% 12% 4 10% 6% 4 4 3 4 5% 25%	5507
April	1st to 10th	Day	18% 12% 4 7% 4 5% 4 3 7% 6% 31%	2400
	11th to 20th	Day	19% 13% 4 7% 5% 4 4 3 4 6% 32%	2374
	21st to end	Day	21% 11% 4 8% 5% 4 4 3 5% 6% 29%	2585
May	1st to 10th	Day	13% 7% 2 5% 4 3 4 3 5% 7% 46%	6042
	11th to 20th	Day	15% 7% 2 5% 3 3 3 3 5% 7% 45%	6319
	21st to end	Day	19% 7% 2 6% 4 4 4 4 5% 7% 37%	6935
June	1st to 10th	Day	12% 5% 2 6% 5% 4 5% 3 5% 8% 46%	2800
	11th to 20th	Day	13% 6% 2 7% 5% 4 5% 4 7% 9% 38%	2800
	21st to end	Day	13% 6% 2 6% 5% 5% 5% 4 7% 9% 40%	2800
July	1st to 10th	Day	9% 4 2 6% 4 4 5% 4 7% 10% 43%	6360
	11th to 20th	Day	8% 4 2 5% 3 4 3 4 5% 8% 54%	6360
	21st to end	Day	8% 5% 2 6% 4 5% 4 4 7% 9% 45%	6748
August	1st to 10th	Day	11% 7% 2 6% 4 5% 4 4 7% 7% 43%	4234
	11th to 20th	Day	13% 6% 2 6% 4 4 4 4 6% 9% 41%	4171
	21st to end	Day	7% 5% 3 6% 4 5% 5% 4 5% 8% 48%	4444
September	1st to 10th	Day	13% 5% 2 5% 4 4 4 4 5% 7% 47%	2400
	11th to 20th	Day	11% 6% 3 5% 4 4 5% 3 5% 8% 47%	2370
	21st to end	Day	12% 7% 2 6% 4 3 4 3 5% 7% 45%	2103
October	1st to 10th	Day	15% 7% 2 6% 4 4 3 3 5% 5% 45%	2000
	11th to 20th	Day	15% 11% 2 6% 3 4 4 3 5% 6% 41%	2000
	21st to end	Day	18% 12% 3 6% 4 3 3 3 5% 6% 37%	2197
November	1st to 10th	Day	11% 11% 3 7% 4 4 4 3 6% 7% 40%	1758
	11th to 20th	Day	11% 15% 6% 10% 5% 4 4 4 5% 5% 31%	1680
	21st to end	Day	12% 13% 4 9% 7% 4 3 3 4 7% 33%	1680
December	1st to 10th	Day	7% 9% 4 13% 12% 8% 6% 4 5% 7% 26%	2690
	11th to 20th	Day	11% 14% 6% 12% 10% 8% 5% 4 5% 5% 19%	3088
	21st to end	Day	17% 20% 7% 21% 5% 4 3 2 3 4 13%	4070
January	1st to 10th	Night	7% 11% 5% 19% 8% 8% 6% 4 5% 5% 22%	6488
	11th to 20th	Night	6% 11% 5% 13% 8% 7% 9% 8% 9% 5% 19%	6311
	21st to end	Night	9% 13% 7% 12% 6% 5% 4 3 5% 5% 31%	6490
February	1st to 10th	Night	8% 14% 6% 11% 7% 5% 5% 4 5% 6% 31%	2600
	11th to 20th	Night	8% 10% 4 9% 6% 6% 6% 4 6% 6% 36%	2533
	21st to end	Night	12% 10% 3 9% 5% 5% 4 3 5% 6% 36%	2070
March	1st to 10th	Night	11% 8% 3 7% 4 3 3 3 4 6% 48%	5039
	11th to 20th	Night	10% 7% 3 6% 4 5% 4 3 6% 9% 43%	4980
	21st to end	Night	23% 12% 5% 9% 4 3 3 3 4 5% 29%	5422
April	1st to 10th	Night	14% 11% 3 7% 4 4 4 3 6% 5% 37%	2000
	11th to 20th	Night	19% 11% 3 7% 5% 4 3 3 5% 5% 36%	1975
	21st to end	Night	20% 11% 3 7% 4 3 3 3 5% 5% 37%	1812
May	1st to 10th	Night	12% 6% 2 6% 3 3 4 3 4 6% 51%	3870
	11th to 20th	Night	14% 7% 2 4 3 3 3 3 4 6% 50%	3596
	21st to end	Night	18% 8% 3 6% 4 3 5% 3 5% 6% 40%	3942
June	1st to 10th	Night	10% 4 2 6% 4 4 4 4 5% 8% 49%	1600
	11th to 20th	Night	11% 5% 2 6% 5% 4 5% 4 7% 9% 42%	1600
	21st to end	Night	10% 5% 1 4 3 2 4 3 6% 8% 54%	1600
July	1st to 10th	Night	8% 4 2 5% 4 4 5% 5% 8% 9% 48%	3618
	11th to 20th	Night	6% 5% 2 4 4 4 3 3 6% 8% 55%	3617
	21st to end	Night	9% 5% 2 4 3 4 4 4 6% 8% 51%	4120
August	1st to 10th	Night	12% 6% 2 6% 4 4 4 3 5% 6% 47%	2926
	11th to 20th	Night	13% 5% 2 4 3 3 3 3 5% 8% 51%	2888
	21st to end	Night	8% 5% 2 6% 4 3 4 4 5% 7% 52%	3458
September	1st to 10th	Night	10% 4 2 6% 3 4 3 3 4 7% 56%	2000
	11th to 20th	Night	11% 5% 2 6% 3 3 3 3 5% 8% 52%	2026
	21st to end	Night	10% 6% 2 5% 3 3 3 3 4 7% 54%	2275
October	1st to 10th	Night	12% 6% 2 6% 4 3 3 4 4 5% 50%	2400
	11th to 20th	Night	15% 8% 2 6% 4 4 4 3 4 7% 43%	2400
	21st to end	Night	18% 10% 3 7% 3 3 3 3 6% 6% 38%	2641
November	1st to 10th	Night	11% 10% 4 6% 5% 3 4 3 5% 6% 43%	2755
	11th to 20th	Night	11% 13% 5% 10% 5% 4 3 3 4 5% 36%	2940
	21st to end	Night	13% 12% 4 9% 5% 4 3 2 4 6% 37%	2940
December	1st to 10th	Night	6% 8% 4 14% 8% 8% 5% 4 6% 7% 30%	4720
	11th to 20th	Night	11% 14% 6% 15% 7% 5% 4 4 5% 5% 24%	5339
	21st to end	Night	20% 15% 7% 18% 6% 4 3 3 4 4 15%	7150

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	71% 3 7% 14% 5%	3698
	11th to 20th	Day	60% 3 8% 16% 13%	3788
	21st to end	Day	62% 3 14% 13% 8%	4488
February	1st to 10th	Day	59% 4 11% 15% 9% 1	1800
	11th to 20th	Day	53% 4 11% 23% 7% 1	1763
	21st to end	Day	53% 4 13% 20% 10% 1	1560
March	1st to 10th	Day	40% 3 15% 28% 12% 2	4847
	11th to 20th	Day	40% 3 12% 31% 12% 2	4980
	21st to end	Day	63% 2 11% 17% 7%	5509
April	1st to 10th	Day	53% 4 11% 21% 10% 1	2400
	11th to 20th	Day	54% 3 12% 19% 11% 1	2374
	21st to end	Day	56% 4 11% 20% 8% 1	2585
May	1st to 10th	Day	38% 3 11% 31% 16% 1	6080
	11th to 20th	Day	39% 3 10% 29% 15% 3	6323
	21st to end	Day	46% 4 11% 29% 9% 1	6949
June	1st to 10th	Day	36% 5% 15% 30% 14% 1	2800
	11th to 20th	Day	42% 4 15% 22% 15% 1	2800
	21st to end	Day	39% 5% 18% 25% 11% 2	2800
July	1st to 10th	Day	37% 3 18% 34% 8%	6291
	11th to 20th	Day	29% 3 15% 36% 16% 1	6285
	21st to end	Day	34% 5% 16% 30% 14% 1	6555
August	1st to 10th	Day	39% 4 13% 31% 12% 2	4220
	11th to 20th	Day	40% 4 16% 30% 10%	4210
	21st to end	Day	34% 4 17% 29% 15% 1	4443
September	1st to 10th	Day	36% 5% 13% 31% 15%	2400
	11th to 20th	Day	36% 4 17% 31% 12% 1	2370
	21st to end	Day	39% 4 11% 32% 15% 1	2103
October	1st to 10th	Day	29% 3 7% 38% 23% 1	3260
	11th to 20th	Day	40% 2 13% 22% 22% 1	3240
	21st to end	Day	43% 2 13% 31% 10%	3523
November	1st to 10th	Day	44% 4 14% 20% 15% 3	1758
	11th to 20th	Day	55% 3 11% 20% 10% 1	1680
	21st to end	Day	52% 3 15% 21% 8% 1	1680
December	1st to 10th	Day	59% 4 15% 15% 7% 1	2690
	11th to 20th	Day	67% 3 14% 12% 4	3085
	21st to end	Day	77% 2 8% 10% 3	4070
January	1st to 10th	Night	64% 4 9% 16% 6%	6488
	11th to 20th	Night	60% 4 10% 14% 11% 1	6311
	21st to end	Night	56% 2 12% 19% 10%	6490
February	1st to 10th	Night	55% 2 11% 21% 10% 2	2600
	11th to 20th	Night	48% 4 12% 25% 10% 1	2534
	21st to end	Night	50% 3 12% 22% 12% 2	2070
March	1st to 10th	Night	39% 2 11% 31% 15% 3	5039
	11th to 20th	Night	38% 3 11% 30% 17% 1	4980
	21st to end	Night	60% 2 10% 16% 10% 2	5422
April	1st to 10th	Night	48% 4 10% 23% 14% 1	2000
	11th to 20th	Night	50% 3 10% 18% 15% 3	1975
	21st to end	Night	50% 3 9% 23% 14% 2	1812
May	1st to 10th	Night	35% 3 10% 28% 22% 2	3897
	11th to 20th	Night	36% 3 10% 24% 20% 7%	3597
	21st to end	Night	46% 3 10% 28% 12% 1	3950
June	1st to 10th	Night	33% 5% 13% 32% 15% 2	1600
	11th to 20th	Night	39% 5% 14% 22% 18% 3	1600
	21st to end	Night	30% 3 17% 30% 19% 2	1600
July	1st to 10th	Night	31% 3 21% 31% 13% 1	3580
	11th to 20th	Night	28% 3 16% 36% 16% 2	3572
	21st to end	Night	32% 4 17% 30% 16% 1	4002
August	1st to 10th	Night	38% 3 13% 28% 16% 3	2916
	11th to 20th	Night	33% 3 16% 32% 15% 1	2915
	21st to end	Night	32% 3 18% 28% 17% 2	3458
September	1st to 10th	Night	29% 4 12% 33% 21% 1	2000
	11th to 20th	Night	32% 2 16% 32% 16% 1	2026
	21st to end	Night	33% 2 12% 32% 20% 2	2275
October	1st to 10th	Night	25% 2 6% 34% 29% 4	3920
	11th to 20th	Night	30% 3 14% 26% 22% 4	3899
	21st to end	Night	45% 2 11% 27% 15% 1	4265
November	1st to 10th	Night	41% 3 14% 25% 14% 2	2755
	11th to 20th	Night	51% 3 12% 20% 13% 1	2940
	21st to end	Night	50% 3 15% 23% 9% 1	2940
December	1st to 10th	Night	53% 3 18% 19% 6% 1	4720
	11th to 20th	Night	63% 3 11% 17% 5% 1	5341
	21st to end	Night	74% 2 8% 11% 4	7150

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	15% 11% 40% 23% 8% 3	330
	11th to 20th	Day	16% 12% 45% 24% 3 1	318
	21st to end	Day	14% 10% 41% 26% 9% 1	330
February	1st to 10th	Day	13% 16% 44% 24% 2 1	300
	11th to 20th	Day	16% 14% 38% 27% 4 1	300
	21st to end	Day	21% 14% 39% 23% 3	249
March	1st to 10th	Day	15% 14% 45% 21% 5%	300
	11th to 20th	Day	20% 14% 34% 24% 6% 1	300
	21st to end	Day	30% 12% 30% 18% 9% 1	350
April	1st to 10th	Day	27% 13% 34% 20% 5%	500
	11th to 20th	Day	26% 18% 25% 23% 7% 1	492
	21st to end	Day	27% 12% 29% 19% 9% 2	685
May	1st to 10th	Day	21% 11% 31% 25% 9% 2	703
	11th to 20th	Day	23% 10% 26% 26% 11% 4	725
	21st to end	Day	20% 9% 27% 26% 15% 3	789
June	1st to 10th	Day	12% 8% 25% 31% 19% 5%	730
	11th to 20th	Day	15% 7% 31% 33% 11% 3	730
	21st to end	Day	16% 8% 31% 27% 14% 5%	730
July	1st to 10th	Day	7% 3 21% 36% 24% 9%	721
	11th to 20th	Day	8% 5% 28% 30% 20% 8%	718
	21st to end	Day	8% 2 23% 39% 22% 6%	794
August	1st to 10th	Day	10% 4 21% 35% 23% 6%	726
	11th to 20th	Day	15% 4 21% 30% 24% 6%	715
	21st to end	Day	10% 4 31% 30% 19% 6%	663
September	1st to 10th	Day	15% 6% 29% 30% 15% 5%	530
	11th to 20th	Day	13% 6% 29% 33% 16% 3	500
	21st to end	Day	16% 10% 29% 25% 13% 6%	330
October	1st to 10th	Day	18% 10% 29% 25% 14% 4	330
	11th to 20th	Day	21% 15% 40% 18% 6% 1	330
	21st to end	Day	27% 16% 34% 15% 7% 1	363
November	1st to 10th	Day	18% 15% 36% 22% 8% 1	330
	11th to 20th	Day	18% 19% 43% 16% 4	330
	21st to end	Day	19% 14% 42% 22% 3	330
December	1st to 10th	Day	15% 12% 44% 24% 5% 1	330
	11th to 20th	Day	18% 15% 38% 22% 5% 1	330
	21st to end	Day	28% 12% 39% 16% 4 1	363
January	1st to 10th	Night	14% 11% 41% 27% 8%	1050
	11th to 20th	Night	17% 13% 38% 27% 5%	1031
	21st to end	Night	18% 11% 37% 27% 6%	1100
February	1st to 10th	Night	15% 12% 41% 26% 5% 1	1000
	11th to 20th	Night	13% 13% 44% 23% 6% 1	979
	21st to end	Night	17% 13% 36% 26% 7% 1	750
March	1st to 10th	Night	18% 10% 41% 23% 8% 1	659
	11th to 20th	Night	19% 10% 37% 25% 8% 1	600
	21st to end	Night	24% 10% 31% 24% 9% 2	660
April	1st to 10th	Night	20% 14% 35% 27% 5%	600
	11th to 20th	Night	24% 11% 32% 27% 6% 1	593
	21st to end	Night	26% 8% 32% 26% 7% 2	600
May	1st to 10th	Night	21% 9% 31% 30% 9% 1	600
	11th to 20th	Night	19% 8% 30% 33% 10% 1	591
	21st to end	Night	18% 6% 27% 35% 12% 1	650
June	1st to 10th	Night	12% 5% 29% 40% 14% 1	600
	11th to 20th	Night	14% 5% 32% 40% 10%	600
	21st to end	Night	12% 3 27% 41% 16% 1	600
July	1st to 10th	Night	8% 2 20% 42% 26% 3	585
	11th to 20th	Night	6% 4 24% 41% 23% 2	582
	21st to end	Night	6% 3 19% 49% 21% 3	657
August	1st to 10th	Night	9% 2 19% 43% 25% 2	597
	11th to 20th	Night	11% 2 21% 39% 22% 4	594
	21st to end	Night	8% 1 26% 42% 21% 3	660
September	1st to 10th	Night	12% 5% 25% 40% 15% 3	600
	11th to 20th	Night	12% 4 32% 35% 16% 2	600
	21st to end	Night	13% 7% 31% 31% 16% 1	675
October	1st to 10th	Night	15% 9% 31% 31% 14% 1	800
	11th to 20th	Night	19% 10% 37% 27% 7% 1	800
	21st to end	Night	24% 11% 31% 27% 6%	880
November	1st to 10th	Night	18% 12% 38% 25% 7% 1	909
	11th to 20th	Night	18% 14% 40% 22% 6%	1050
	21st to end	Night	18% 14% 41% 21% 6%	1050
December	1st to 10th	Night	15% 11% 41% 26% 6% 1	1050
	11th to 20th	Night	19% 11% 41% 23% 6%	1050
	21st to end	Night	25% 12% 34% 24% 5%	1155

Page generated at 2026-01-14 00:14:26. Version ac07

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