Jackson (WI)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jackson (WI) clear sky chart from 2005-11-06 to 2026-02-01.

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% 8% 3 8% 5% 4 5% 4 6% 7% 38%	127590
	Night	12% 9% 3 8% 5% 4 4 3 5% 7% 39%	124677
Transparency	Day	43% 5% 12% 25% 14% 1	131090
	Night	44% 4 12% 23% 15% 2	129251
Seeing	Day	16% 12% 30% 26% 12% 4	17564
	Night	17% 10% 31% 28% 12% 1	27532

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	9% 10% 5% 12% 6% 5% 6% 4 5% 7% 30%	3697
	11th to 20th	Day	8% 10% 5% 11% 5% 4 5% 5% 6% 7% 33%	3700
	21st to end	Day	12% 15% 6% 8% 4 3 3 3 5% 6% 35%	4084
February	1st to 10th	Day	10% 13% 6% 9% 5% 3 4 5% 5% 7% 31%	1800
	11th to 20th	Day	13% 11% 4 8% 4 4 5% 4 5% 5% 36%	1942
	21st to end	Day	11% 14% 4 10% 5% 5% 5% 4 5% 7% 31%	1650
March	1st to 10th	Day	13% 8% 3 7% 4 3 4 3 5% 6% 44%	4480
	11th to 20th	Day	10% 7% 3 7% 5% 5% 5% 4 6% 7% 42%	4673
	21st to end	Day	20% 13% 4 10% 5% 4 4 3 4 5% 28%	5967
April	1st to 10th	Day	17% 13% 3 7% 6% 4 4 4 5% 5% 31%	2400
	11th to 20th	Day	16% 9% 4 8% 5% 5% 5% 3 5% 6% 34%	2374
	21st to end	Day	17% 10% 3 7% 4 4 5% 4 6% 7% 32%	2540
May	1st to 10th	Day	14% 9% 3 6% 4 4 4 3 5% 7% 41%	5898
	11th to 20th	Day	12% 6% 2 7% 4 5% 5% 4 6% 8% 41%	6319
	21st to end	Day	15% 7% 2 6% 4 4 4 4 6% 8% 39%	6935
June	1st to 10th	Day	9% 6% 2 6% 5% 4 4 4 7% 8% 45%	2800
	11th to 20th	Day	11% 6% 2 7% 5% 4 4 4 7% 8% 42%	2800
	21st to end	Day	9% 6% 2 6% 4 4 5% 5% 7% 9% 42%	2800
July	1st to 10th	Day	10% 6% 3 7% 4 4 5% 5% 7% 10% 38%	6360
	11th to 20th	Day	6% 4 2 6% 4 5% 6% 5% 7% 10% 46%	6360
	21st to end	Day	8% 6% 2 7% 4 4 5% 4 7% 9% 45%	6924
August	1st to 10th	Day	9% 5% 2 7% 4 5% 6% 4 7% 9% 41%	4549
	11th to 20th	Day	11% 5% 2 6% 4 5% 5% 4 7% 8% 43%	3947
	21st to end	Day	9% 6% 3 7% 4 4 4 4 6% 9% 43%	4312
September	1st to 10th	Day	10% 6% 2 6% 5% 4 5% 5% 5% 7% 45%	2400
	11th to 20th	Day	11% 5% 2 5% 3 4 5% 3 5% 8% 49%	2281
	21st to end	Day	12% 7% 2 6% 5% 4 4 4 5% 8% 44%	2200
October	1st to 10th	Day	13% 7% 2 6% 4 4 4 4 5% 8% 45%	2125
	11th to 20th	Day	19% 8% 3 7% 5% 4 4 4 6% 7% 31%	1965
	21st to end	Day	16% 8% 3 7% 4 4 5% 5% 4 6% 37%	1980
November	1st to 10th	Day	10% 9% 3 8% 5% 4 4 3 5% 6% 43%	1852
	11th to 20th	Day	10% 11% 3 10% 6% 6% 5% 4 5% 8% 33%	1890
	21st to end	Day	15% 12% 4 7% 5% 4 4 4 4 6% 35%	1738
December	1st to 10th	Day	8% 9% 4 9% 5% 5% 4 4 7% 9% 36%	2690
	11th to 20th	Day	12% 14% 5% 8% 5% 5% 4 4 7% 7% 28%	3088
	21st to end	Day	20% 19% 7% 13% 4 4 4 2 4 4 18%	4070
January	1st to 10th	Night	10% 10% 5% 12% 6% 4 4 3 4 5% 36%	6488
	11th to 20th	Night	10% 11% 5% 13% 7% 5% 6% 5% 6% 6% 26%	6500
	21st to end	Night	11% 13% 5% 9% 5% 4 4 3 5% 6% 33%	7132
February	1st to 10th	Night	12% 14% 3 9% 5% 4 4 4 5% 5% 35%	2601
	11th to 20th	Night	11% 9% 3 8% 5% 5% 5% 4 5% 6% 40%	2343
	21st to end	Night	16% 12% 3 7% 4 4 4 3 5% 7% 35%	1980
March	1st to 10th	Night	15% 8% 3 5% 3 3 4 3 5% 6% 44%	5373
	11th to 20th	Night	10% 6% 2 5% 4 5% 4 4 6% 9% 45%	5316
	21st to end	Night	18% 11% 4 11% 5% 4 4 3 4 5% 31%	4962
April	1st to 10th	Night	16% 9% 3 7% 5% 4 4 3 5% 6% 37%	2000
	11th to 20th	Night	19% 9% 3 6% 4 3 4 3 5% 6% 38%	1975
	21st to end	Night	16% 8% 3 6% 3 4 5% 4 6% 6% 39%	1860
May	1st to 10th	Night	15% 8% 3 6% 5% 4 5% 3 5% 8% 39%	3997
	11th to 20th	Night	9% 6% 3 8% 5% 5% 5% 4 6% 7% 41%	3596
	21st to end	Night	16% 8% 2 6% 4 4 4 4 5% 7% 40%	3942
June	1st to 10th	Night	10% 5% 2 5% 4 5% 5% 3 6% 9% 46%	1600
	11th to 20th	Night	12% 6% 2 5% 4 4 4 5% 6% 9% 43%	1600
	21st to end	Night	9% 7% 2 6% 5% 4 4 3 6% 7% 47%	1600
July	1st to 10th	Night	9% 6% 2 7% 4 4 5% 4 6% 9% 44%	3618
	11th to 20th	Night	5% 5% 2 5% 4 4 4 4 6% 8% 53%	3617
	21st to end	Night	6% 4 2 5% 4 5% 5% 4 6% 8% 51%	3947
August	1st to 10th	Night	10% 5% 2 5% 3 4 5% 4 6% 8% 48%	2597
	11th to 20th	Night	9% 6% 2 5% 4 4 4 3 6% 8% 49%	3098
	21st to end	Night	7% 5% 2 5% 4 4 4 4 6% 9% 50%	3586
September	1st to 10th	Night	8% 5% 2 6% 3 3 4 3 4 7% 55%	2000
	11th to 20th	Night	10% 3 1 5% 4 4 4 4 5% 7% 54%	2097
	21st to end	Night	11% 7% 2 7% 4 3 4 3 4 7% 48%	2200
October	1st to 10th	Night	13% 6% 2 5% 4 4 3 3 4 6% 49%	2273
	11th to 20th	Night	16% 7% 2 6% 4 3 4 3 5% 7% 42%	2434
	21st to end	Night	17% 8% 3 6% 4 4 4 3 6% 8% 37%	2860
November	1st to 10th	Night	12% 7% 3 6% 4 3 4 4 5% 6% 45%	2666
	11th to 20th	Night	13% 8% 3 8% 5% 5% 5% 3 6% 7% 36%	2730
	21st to end	Night	15% 10% 3 6% 5% 5% 5% 3 5% 6% 36%	2880
December	1st to 10th	Night	9% 10% 3 6% 4 4 4 3 5% 7% 44%	4720
	11th to 20th	Night	14% 16% 5% 9% 5% 4 5% 3 5% 5% 29%	5339
	21st to end	Night	19% 19% 6% 11% 5% 5% 4 3 4 5% 21%	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	54% 4 13% 20% 9%	3698
	11th to 20th	Day	50% 4 10% 17% 17% 2	3700
	21st to end	Day	52% 3 9% 21% 14%	4084
February	1st to 10th	Day	52% 4 12% 21% 10% 1	1800
	11th to 20th	Day	49% 4 10% 24% 11% 2	1952
	21st to end	Day	53% 4 11% 18% 11% 2	1650
March	1st to 10th	Day	41% 4 11% 26% 13% 6%	4480
	11th to 20th	Day	41% 4 14% 24% 15% 2	4673
	21st to end	Day	58% 3 11% 15% 11% 1	5969
April	1st to 10th	Day	53% 5% 11% 19% 11% 1	2400
	11th to 20th	Day	50% 5% 11% 20% 13% 2	2374
	21st to end	Day	50% 6% 12% 20% 11% 1	2540
May	1st to 10th	Day	43% 4 10% 25% 16% 1	5933
	11th to 20th	Day	40% 6% 15% 25% 14% 1	6323
	21st to end	Day	41% 6% 11% 28% 13% 2	6949
June	1st to 10th	Day	36% 5% 14% 27% 16% 2	2800
	11th to 20th	Day	38% 6% 15% 24% 16% 1	2800
	21st to end	Day	36% 7% 15% 25% 15% 2	2800
July	1st to 10th	Day	39% 7% 12% 31% 11% 1	6291
	11th to 20th	Day	32% 6% 14% 32% 14% 1	6285
	21st to end	Day	34% 6% 16% 24% 18% 1	6728
August	1st to 10th	Day	37% 6% 14% 30% 11% 1	4534
	11th to 20th	Day	36% 7% 12% 33% 12% 1	3986
	21st to end	Day	37% 6% 13% 25% 18% 1	4311
September	1st to 10th	Day	37% 7% 11% 28% 16% 2	2400
	11th to 20th	Day	34% 4 13% 32% 17% 1	2281
	21st to end	Day	40% 4 11% 31% 13% 1	2200
October	1st to 10th	Day	25% 3 6% 40% 25% 1	3463
	11th to 20th	Day	38% 4 9% 27% 21% 1	3181
	21st to end	Day	41% 4 11% 29% 14% 2	3180
November	1st to 10th	Day	42% 4 13% 26% 14% 2	1852
	11th to 20th	Day	50% 4 13% 22% 10% 1	1890
	21st to end	Day	50% 5% 12% 25% 8%	1738
December	1st to 10th	Day	43% 5% 20% 24% 7% 1	2690
	11th to 20th	Day	54% 5% 12% 18% 10% 1	3085
	21st to end	Day	71% 3 7% 12% 7%	4070
January	1st to 10th	Night	52% 3 8% 22% 15% 1	6488
	11th to 20th	Night	58% 3 9% 12% 17% 1	6500
	21st to end	Night	52% 3 13% 18% 12% 1	7132
February	1st to 10th	Night	51% 4 10% 20% 13% 2	2601
	11th to 20th	Night	45% 4 10% 24% 15% 2	2344
	21st to end	Night	49% 3 13% 20% 12% 3	1980
March	1st to 10th	Night	42% 3 13% 25% 13% 4	5373
	11th to 20th	Night	36% 3 14% 28% 15% 4	5316
	21st to end	Night	57% 3 10% 16% 12% 2	4962
April	1st to 10th	Night	47% 4 9% 21% 17% 1	2000
	11th to 20th	Night	47% 4 7% 21% 17% 3	1975
	21st to end	Night	44% 4 12% 24% 14% 2	1860
May	1st to 10th	Night	44% 3 13% 20% 18% 2	4024
	11th to 20th	Night	41% 5% 15% 21% 17% 2	3597
	21st to end	Night	44% 4 9% 25% 13% 5%	3950
June	1st to 10th	Night	33% 6% 14% 28% 18% 2	1600
	11th to 20th	Night	37% 5% 11% 25% 20% 2	1600
	21st to end	Night	37% 4 16% 23% 18% 2	1600
July	1st to 10th	Night	36% 5% 13% 33% 10% 3	3580
	11th to 20th	Night	28% 5% 15% 32% 18% 2	3572
	21st to end	Night	30% 5% 16% 23% 23% 3	3832
August	1st to 10th	Night	33% 5% 15% 26% 19% 2	2588
	11th to 20th	Night	33% 5% 14% 33% 15% 1	3125
	21st to end	Night	31% 5% 13% 28% 21% 3	3586
September	1st to 10th	Night	30% 5% 12% 28% 23% 2	2000
	11th to 20th	Night	32% 4 9% 35% 18% 1	2097
	21st to end	Night	38% 3 10% 32% 16% 1	2200
October	1st to 10th	Night	26% 3 7% 39% 23% 1	3715
	11th to 20th	Night	35% 3 13% 26% 21% 3	3957
	21st to end	Night	42% 4 9% 27% 17% 1	4610
November	1st to 10th	Night	39% 4 11% 27% 17% 2	2666
	11th to 20th	Night	47% 5% 13% 22% 11% 2	2730
	21st to end	Night	48% 5% 14% 23% 9% 1	2880
December	1st to 10th	Night	41% 4 18% 27% 7% 3	4720
	11th to 20th	Night	58% 4 10% 15% 12% 1	5341
	21st to end	Night	67% 4 8% 14% 7%	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	16% 17% 39% 22% 5% 1	330
	11th to 20th	Day	15% 22% 35% 24% 4 1	330
	21st to end	Day	22% 17% 39% 18% 4 1	363
February	1st to 10th	Day	14% 20% 45% 14% 6% 1	300
	11th to 20th	Day	18% 25% 38% 14% 5%	300
	21st to end	Day	22% 23% 42% 12%	249
March	1st to 10th	Day	17% 23% 43% 14% 2	300
	11th to 20th	Day	23% 20% 32% 18% 6% 1	322
	21st to end	Day	27% 15% 29% 22% 6% 1	550
April	1st to 10th	Day	26% 14% 36% 20% 4	500
	11th to 20th	Day	20% 21% 28% 21% 8% 2	492
	21st to end	Day	22% 13% 30% 24% 11% 1	500
May	1st to 10th	Day	22% 11% 34% 24% 7% 2	513
	11th to 20th	Day	19% 11% 31% 25% 10% 3	725
	21st to end	Day	16% 7% 33% 27% 12% 5%	789
June	1st to 10th	Day	9% 9% 32% 33% 13% 4	730
	11th to 20th	Day	14% 8% 29% 32% 12% 5%	730
	21st to end	Day	11% 8% 32% 30% 15% 4	730
July	1st to 10th	Day	9% 3 20% 35% 24% 9%	721
	11th to 20th	Day	8% 6% 26% 34% 19% 7%	718
	21st to end	Day	7% 3 26% 37% 20% 6%	794
August	1st to 10th	Day	7% 3 24% 37% 19% 10%	725
	11th to 20th	Day	12% 4 16% 30% 25% 12%	519
	21st to end	Day	11% 6% 19% 33% 22% 9%	583
September	1st to 10th	Day	11% 9% 23% 28% 21% 8%	530
	11th to 20th	Day	9% 4 21% 31% 25% 10%	530
	21st to end	Day	15% 11% 24% 26% 17% 6%	530
October	1st to 10th	Day	18% 9% 25% 27% 14% 5%	455
	11th to 20th	Day	20% 18% 34% 19% 8%	330
	21st to end	Day	23% 15% 37% 20% 4 1	363
November	1st to 10th	Day	16% 20% 35% 20% 8% 1	330
	11th to 20th	Day	18% 20% 35% 19% 8%	330
	21st to end	Day	24% 12% 42% 18% 4	330
December	1st to 10th	Day	18% 20% 38% 16% 6% 1	330
	11th to 20th	Day	21% 22% 35% 16% 5% 1	330
	21st to end	Day	26% 20% 35% 14% 3 1	363
January	1st to 10th	Night	18% 18% 36% 23% 5%	1050
	11th to 20th	Night	20% 16% 39% 18% 6% 1	1050
	21st to end	Night	18% 15% 38% 24% 5%	1155
February	1st to 10th	Night	19% 14% 37% 24% 5%	1001
	11th to 20th	Night	18% 17% 36% 24% 4	788
	21st to end	Night	23% 16% 39% 18% 4	660
March	1st to 10th	Night	20% 12% 36% 24% 8% 1	800
	11th to 20th	Night	14% 15% 37% 26% 7%	777
	21st to end	Night	22% 7% 29% 32% 9% 1	660
April	1st to 10th	Night	21% 12% 34% 26% 7%	600
	11th to 20th	Night	24% 10% 32% 25% 7% 1	593
	21st to end	Night	22% 6% 30% 29% 12% 1	600
May	1st to 10th	Night	17% 8% 31% 36% 8% 1	600
	11th to 20th	Night	19% 5% 30% 31% 14% 1	591
	21st to end	Night	13% 4 24% 37% 19% 2	650
June	1st to 10th	Night	12% 3 26% 41% 18% 1	600
	11th to 20th	Night	14% 3 30% 36% 16% 2	600
	21st to end	Night	11% 3 26% 42% 17% 1	600
July	1st to 10th	Night	9% 3 14% 41% 29% 4	585
	11th to 20th	Night	7% 2 20% 43% 24% 4	582
	21st to end	Night	7% 2 19% 44% 27% 1	657
August	1st to 10th	Night	8% 2 17% 43% 28% 3	597
	11th to 20th	Night	10% 3 15% 38% 29% 5%	594
	21st to end	Night	9% 2 18% 40% 27% 4	660
September	1st to 10th	Night	9% 4 21% 35% 25% 6%	600
	11th to 20th	Night	11% 4 19% 31% 28% 6%	697
	21st to end	Night	14% 8% 23% 29% 22% 5%	800
October	1st to 10th	Night	16% 7% 27% 32% 17% 1	800
	11th to 20th	Night	20% 12% 32% 27% 8% 1	800
	21st to end	Night	22% 11% 32% 26% 9% 1	880
November	1st to 10th	Night	17% 11% 38% 24% 9% 1	820
	11th to 20th	Night	18% 17% 35% 21% 7%	840
	21st to end	Night	21% 14% 37% 22% 6%	990
December	1st to 10th	Night	22% 16% 37% 21% 4	1050
	11th to 20th	Night	23% 14% 37% 20% 5% 1	1050
	21st to end	Night	28% 15% 35% 18% 3	1155

Page generated at 2026-01-29 00:21:47. Version ac07

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