Sauk Mountain Overlook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sauk Mountain Overlook clear sky chart from 2005-11-06 to 2026-07-01.

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	22% 13% 3 7% 4 4 4 3 4 5% 30%	142025
	Night	24% 15% 3 7% 4 3 4 3 4 5% 28%	138982
Transparency	Day	55% 7% 12% 16% 8% 1	141741
	Night	58% 7% 12% 15% 8% 1	138848
Seeing	Day	30% 12% 25% 22% 9% 2	17108
	Night	36% 8% 22% 24% 10%	25469

By Month

Percentage Cloud Cover NW (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	33% 28% 6% 8% 3 3 2 3 3 3 7%	4125
	11th to 20th	Day	20% 10% 3 6% 3 3 4 3 4 6% 38%	4696
	21st to end	Day	30% 13% 3 5% 3 3 3 3 4 4 27%	5186
February	1st to 10th	Day	31% 18% 4 6% 4 4 4 3 5% 5% 17%	1872
	11th to 20th	Day	26% 21% 4 7% 4 4 3 3 3 4 20%	1845
	21st to end	Day	21% 26% 5% 10% 5% 3 4 2 3 4 17%	1644
March	1st to 10th	Day	20% 21% 5% 10% 6% 4 4 3 4 5% 20%	4618
	11th to 20th	Day	18% 22% 5% 10% 6% 4 4 2 3 3 23%	5110
	21st to end	Day	26% 19% 4 11% 6% 5% 5% 3 4 5% 14%	5866
April	1st to 10th	Day	27% 21% 4 7% 5% 5% 4 3 4 5% 15%	2520
	11th to 20th	Day	25% 17% 4 9% 5% 4 4 3 4 5% 20%	2502
	21st to end	Day	29% 16% 3 8% 5% 3 4 2 4 5% 20%	2836
May	1st to 10th	Day	14% 10% 3 7% 5% 5% 5% 4 6% 7% 35%	8195
	11th to 20th	Day	22% 13% 4 9% 6% 5% 5% 4 5% 6% 21%	8160
	21st to end	Day	24% 9% 3 8% 5% 5% 4 4 6% 7% 25%	8993
June	1st to 10th	Day	31% 10% 2 7% 4 5% 5% 3 4 5% 24%	3018
	11th to 20th	Day	32% 11% 4 8% 5% 4 4 3 5% 5% 18%	3150
	21st to end	Day	20% 9% 3 8% 6% 5% 4 4 5% 5% 31%	3150
July	1st to 10th	Day	11% 3 2 3 2 3 3 3 5% 6% 59%	6781
	11th to 20th	Day	6% 4 1 4 3 3 3 3 4 4 65%	6515
	21st to end	Day	11% 4 2 4 3 3 4 3 6% 8% 51%	6874
August	1st to 10th	Day	9% 4 2 3 2 2 3 3 5% 7% 59%	4541
	11th to 20th	Day	15% 8% 2 8% 4 4 4 4 6% 8% 37%	4195
	21st to end	Day	17% 8% 3 8% 5% 4 4 3 4 6% 38%	4450
September	1st to 10th	Day	15% 7% 3 6% 4 3 4 3 5% 6% 46%	2400
	11th to 20th	Day	19% 8% 3 6% 5% 4 4 3 4 5% 39%	2400
	21st to end	Day	27% 7% 3 5% 3 3 3 3 4 5% 37%	2127
October	1st to 10th	Day	20% 9% 3 6% 4 4 4 4 7% 8% 31%	3280
	11th to 20th	Day	34% 11% 2 6% 4 3 3 3 4 5% 25%	3261
	21st to end	Day	32% 14% 4 9% 5% 5% 5% 3 4 5% 16%	3273
November	1st to 10th	Day	39% 13% 4 6% 4 3 4 4 5% 3 16%	1698
	11th to 20th	Day	40% 16% 3 7% 3 3 2 2 3 3 18%	1680
	21st to end	Day	37% 18% 4 5% 3 3 3 2 3 4 17%	1680
December	1st to 10th	Day	24% 13% 4 5% 4 4 4 3 5% 6% 29%	2700
	11th to 20th	Day	28% 24% 6% 10% 4 4 3 3 3 3 13%	3105
	21st to end	Day	31% 24% 5% 9% 4 5% 3 2 3 4 9%	3579
January	1st to 10th	Night	28% 26% 6% 9% 4 4 4 3 3 3 9%	8770
	11th to 20th	Night	23% 11% 3 5% 2 2 2 3 5% 7% 36%	8183
	21st to end	Night	28% 13% 3 6% 4 3 3 3 4 4 29%	8994
February	1st to 10th	Night	30% 20% 4 8% 5% 4 3 3 4 4 16%	2746
	11th to 20th	Night	25% 24% 4 8% 4 3 2 3 4 3 20%	2662
	21st to end	Night	27% 23% 3 8% 4 3 3 3 3 4 18%	2161
March	1st to 10th	Night	18% 23% 5% 9% 4 4 4 3 5% 5% 21%	5480
	11th to 20th	Night	21% 24% 4 8% 4 3 2 2 3 4 24%	5109
	21st to end	Night	31% 25% 5% 9% 4 3 3 2 3 4 13%	5350
April	1st to 10th	Night	27% 20% 3 7% 5% 4 4 3 4 5% 19%	2100
	11th to 20th	Night	26% 17% 3 7% 5% 4 4 3 4 5% 22%	2066
	21st to end	Night	32% 14% 3 7% 4 4 3 2 3 4 23%	1782
May	1st to 10th	Night	13% 11% 3 6% 4 4 4 4 5% 5% 42%	4724
	11th to 20th	Night	24% 14% 3 7% 4 4 4 3 5% 6% 25%	4700
	21st to end	Night	22% 8% 3 7% 4 5% 6% 4 5% 8% 28%	5178
June	1st to 10th	Night	26% 9% 3 7% 4 4 5% 4 5% 6% 28%	1597
	11th to 20th	Night	25% 12% 3 7% 5% 4 3 4 5% 5% 26%	1470
	21st to end	Night	17% 8% 3 7% 4 5% 5% 3 6% 6% 37%	1470
July	1st to 10th	Night	10% 5% 1 4 2 3 2 2 3 5% 62%	3180
	11th to 20th	Night	5% 2 1 3 2 2 2 2 4 5% 73%	3428
	21st to end	Night	8% 3 2 4 3 3 3 3 4 6% 59%	3969
August	1st to 10th	Night	7% 2 1 3 3 3 3 3 5% 7% 64%	2609
	11th to 20th	Night	13% 7% 3 7% 3 4 4 3 5% 6% 46%	2858
	21st to end	Night	19% 6% 2 5% 3 3 4 3 4 6% 43%	3466
September	1st to 10th	Night	13% 7% 2 6% 3 4 4 3 4 6% 49%	2000
	11th to 20th	Night	22% 9% 3 6% 4 3 4 3 4 5% 38%	2000
	21st to end	Night	26% 8% 3 6% 3 3 4 3 5% 5% 34%	2269
October	1st to 10th	Night	19% 8% 3 7% 4 4 5% 5% 7% 8% 30%	3920
	11th to 20th	Night	35% 10% 3 4 3 3 3 3 4 5% 28%	3897
	21st to end	Night	33% 16% 4 8% 4 4 3 3 4 4 18%	4528
November	1st to 10th	Night	39% 16% 3 6% 5% 4 4 2 3 4 13%	2816
	11th to 20th	Night	42% 15% 3 6% 3 3 2 2 4 4 16%	2940
	21st to end	Night	37% 17% 3 8% 3 3 3 2 3 3 17%	2940
December	1st to 10th	Night	22% 14% 3 7% 4 4 4 3 6% 7% 27%	4700
	11th to 20th	Night	33% 21% 4 9% 5% 3 3 2 4 3 11%	5320
	21st to end	Night	31% 25% 5% 9% 4 3 4 2 3 3 8%	7600

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	82% 4 5% 7% 1	4125
	11th to 20th	Day	47% 5% 10% 22% 14% 3	4720
	21st to end	Day	61% 4 5% 18% 11% 1	5187
February	1st to 10th	Day	69% 6% 7% 9% 7% 1	1872
	11th to 20th	Day	69% 5% 7% 10% 8% 1	1854
	21st to end	Day	73% 6% 6% 11% 4 1	1644
March	1st to 10th	Day	66% 6% 9% 11% 8%	4618
	11th to 20th	Day	68% 6% 8% 17% 1	5110
	21st to end	Day	73% 8% 9% 8% 2	5866
April	1st to 10th	Day	73% 7% 11% 8% 1	2520
	11th to 20th	Day	67% 6% 10% 10% 6% 1	2502
	21st to end	Day	69% 6% 9% 10% 5%	2836
May	1st to 10th	Day	46% 8% 17% 24% 5%	8195
	11th to 20th	Day	61% 12% 16% 10% 1	8163
	21st to end	Day	56% 10% 21% 12% 1	8994
June	1st to 10th	Day	63% 7% 13% 11% 6% 1	3018
	11th to 20th	Day	69% 7% 9% 11% 3	3150
	21st to end	Day	54% 9% 11% 19% 6% 1	3150
July	1st to 10th	Day	25% 7% 21% 20% 19% 8%	6707
	11th to 20th	Day	21% 6% 16% 28% 26% 3	6435
	21st to end	Day	27% 7% 23% 30% 10% 2	6681
August	1st to 10th	Day	23% 7% 13% 30% 26% 1	4524
	11th to 20th	Day	42% 10% 17% 20% 9% 2	4235
	21st to end	Day	46% 8% 11% 24% 11% 1	4449
September	1st to 10th	Day	40% 7% 11% 21% 15% 6%	2400
	11th to 20th	Day	47% 7% 9% 17% 15% 3	2400
	21st to end	Day	50% 7% 14% 15% 11% 3	2127
October	1st to 10th	Day	46% 10% 13% 25% 6%	3280
	11th to 20th	Day	62% 6% 9% 12% 10% 1	3261
	21st to end	Day	68% 8% 7% 9% 7%	3273
November	1st to 10th	Day	73% 7% 7% 8% 4	1698
	11th to 20th	Day	74% 4 5% 8% 7% 2	1680
	21st to end	Day	73% 4 5% 9% 8% 2	1680
December	1st to 10th	Day	58% 5% 8% 17% 11% 1	2700
	11th to 20th	Day	77% 5% 7% 9% 2	3108
	21st to end	Day	80% 6% 7% 5% 2	3579
January	1st to 10th	Night	79% 5% 6% 8% 2	8770
	11th to 20th	Night	48% 5% 10% 19% 16% 2	8221
	21st to end	Night	59% 4 9% 17% 10%	8994
February	1st to 10th	Night	72% 5% 7% 9% 6% 1	2746
	11th to 20th	Night	69% 5% 7% 10% 7% 2	2664
	21st to end	Night	71% 5% 8% 11% 4	2161
March	1st to 10th	Night	63% 7% 11% 11% 8%	5480
	11th to 20th	Night	65% 7% 10% 17% 2	5110
	21st to end	Night	76% 7% 11% 6%	5350
April	1st to 10th	Night	70% 8% 12% 9% 1	2100
	11th to 20th	Night	64% 8% 12% 10% 6% 1	2066
	21st to end	Night	67% 8% 10% 11% 5%	1782
May	1st to 10th	Night	44% 8% 17% 27% 4	4721
	11th to 20th	Night	58% 13% 16% 12% 2	4700
	21st to end	Night	53% 11% 22% 13% 1	5182
June	1st to 10th	Night	57% 9% 16% 12% 5% 1	1597
	11th to 20th	Night	59% 10% 13% 15% 3	1470
	21st to end	Night	48% 10% 16% 18% 6% 1	1470
July	1st to 10th	Night	27% 6% 18% 23% 21% 6%	3145
	11th to 20th	Night	16% 6% 19% 23% 33% 3	3385
	21st to end	Night	25% 8% 22% 29% 14% 2	3857
August	1st to 10th	Night	21% 7% 17% 33% 21% 1	2601
	11th to 20th	Night	36% 10% 24% 19% 9% 2	2884
	21st to end	Night	41% 7% 15% 25% 10% 1	3466
September	1st to 10th	Night	37% 8% 14% 23% 15% 4	2000
	11th to 20th	Night	50% 6% 10% 17% 14% 3	2000
	21st to end	Night	52% 7% 13% 17% 9% 2	2269
October	1st to 10th	Night	48% 9% 15% 22% 5%	3920
	11th to 20th	Night	59% 5% 10% 16% 9%	3897
	21st to end	Night	68% 6% 8% 10% 7%	4528
November	1st to 10th	Night	75% 6% 8% 7% 3 1	2816
	11th to 20th	Night	74% 5% 7% 8% 5% 1	2940
	21st to end	Night	74% 4 5% 8% 8% 2	2940
December	1st to 10th	Night	56% 6% 10% 18% 9% 1	4700
	11th to 20th	Night	76% 5% 6% 9% 3	5316
	21st to end	Night	81% 6% 5% 5% 2	7600

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	45% 16% 18% 15% 6%	220
	11th to 20th	Day	41% 9% 20% 20% 10%	220
	21st to end	Day	42% 7% 21% 21% 7% 1	242
February	1st to 10th	Day	42% 11% 27% 15% 4 1	412
	11th to 20th	Day	41% 14% 22% 16% 7% 1	425
	21st to end	Day	38% 14% 26% 16% 6%	402
March	1st to 10th	Day	39% 15% 22% 19% 5%	540
	11th to 20th	Day	38% 17% 18% 19% 7% 1	540
	21st to end	Day	41% 16% 23% 17% 4	594
April	1st to 10th	Day	39% 14% 21% 17% 9%	540
	11th to 20th	Day	33% 18% 23% 18% 8% 1	532
	21st to end	Day	38% 13% 23% 19% 7% 1	540
May	1st to 10th	Day	23% 15% 29% 26% 6%	543
	11th to 20th	Day	32% 11% 25% 22% 9% 1	568
	21st to end	Day	32% 12% 25% 20% 9% 2	617
June	1st to 10th	Day	29% 15% 26% 21% 8% 2	648
	11th to 20th	Day	32% 15% 29% 18% 5% 1	780
	21st to end	Day	22% 12% 27% 28% 11% 1	780
July	1st to 10th	Day	17% 9% 31% 33% 9% 1	722
	11th to 20th	Day	14% 10% 30% 30% 13% 3	610
	21st to end	Day	10% 7% 30% 31% 15% 6%	575
August	1st to 10th	Day	16% 6% 26% 32% 15% 5%	527
	11th to 20th	Day	10% 8% 28% 33% 17% 4	517
	21st to end	Day	16% 12% 28% 27% 14% 4	583
September	1st to 10th	Day	18% 11% 27% 26% 13% 5%	530
	11th to 20th	Day	24% 9% 25% 30% 11% 1	530
	21st to end	Day	28% 12% 25% 23% 11% 2	530
October	1st to 10th	Day	29% 9% 24% 20% 15% 2	530
	11th to 20th	Day	40% 9% 18% 19% 12% 2	530
	21st to end	Day	38% 14% 23% 15% 8% 1	412
November	1st to 10th	Day	40% 11% 28% 16% 6%	247
	11th to 20th	Day	49% 12% 15% 15% 7% 2	220
	21st to end	Day	45% 10% 22% 13% 9% 1	220
December	1st to 10th	Day	50% 7% 9% 15% 15% 3	220
	11th to 20th	Day	45% 15% 20% 14% 6%	220
	21st to end	Day	40% 14% 26% 14% 5%	242
January	1st to 10th	Night	53% 10% 18% 17% 2	950
	11th to 20th	Night	42% 9% 25% 21% 3	840
	21st to end	Night	42% 8% 24% 22% 4	924
February	1st to 10th	Night	42% 11% 28% 16% 3	840
	11th to 20th	Night	39% 8% 29% 18% 5%	824
	21st to end	Night	41% 11% 27% 17% 4	692
March	1st to 10th	Night	36% 11% 23% 23% 6%	840
	11th to 20th	Night	43% 13% 20% 18% 6%	840
	21st to end	Night	42% 11% 25% 16% 5%	924
April	1st to 10th	Night	38% 9% 20% 25% 7%	840
	11th to 20th	Night	36% 9% 26% 23% 6%	818
	21st to end	Night	41% 5% 25% 23% 7%	522
May	1st to 10th	Night	25% 9% 26% 33% 7%	420
	11th to 20th	Night	26% 6% 21% 34% 12%	414
	21st to end	Night	29% 5% 20% 32% 13%	455
June	1st to 10th	Night	30% 7% 18% 31% 13%	420
	11th to 20th	Night	30% 5% 25% 28% 12%	420
	21st to end	Night	19% 5% 25% 35% 17%	420
July	1st to 10th	Night	15% 4 18% 36% 26% 1	390
	11th to 20th	Night	12% 5% 14% 38% 30% 1	388
	21st to end	Night	10% 2 14% 33% 39% 2	438
August	1st to 10th	Night	13% 2 10% 31% 43% 2	398
	11th to 20th	Night	12% 2 10% 39% 36% 1	562
	21st to end	Night	18% 3 15% 40% 23%	790
September	1st to 10th	Night	16% 5% 21% 36% 22% 1	800
	11th to 20th	Night	25% 4 19% 30% 22%	800
	21st to end	Night	31% 3 19% 34% 12%	800
October	1st to 10th	Night	30% 4 23% 30% 13%	800
	11th to 20th	Night	39% 7% 20% 27% 7%	800
	21st to end	Night	42% 9% 25% 19% 4	880
November	1st to 10th	Night	48% 8% 25% 18% 1	820
	11th to 20th	Night	52% 10% 18% 16% 4	840
	21st to end	Night	46% 10% 22% 17% 5%	840
December	1st to 10th	Night	38% 8% 29% 19% 5%	840
	11th to 20th	Night	50% 12% 23% 12% 1	840
	21st to end	Night	50% 12% 23% 13% 1	1040

Page generated at 2026-06-27 23:10:49. Version ac07

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