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 2025-02-25.

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	24% 13% 3 7% 4 4 4 3 4 5% 30%	112546
	Night	26% 15% 3 7% 4 3 3 3 4 5% 27%	114740
Transparency	Day	57% 7% 10% 16% 9% 2	112303
	Night	60% 7% 11% 14% 8% 1	114629
Seeing	Day	31% 12% 25% 22% 9% 2	15298
	Night	37% 8% 22% 24% 10%	23859

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% 25% 6% 8% 4 3 2 3 4 4 9%	3179
	11th to 20th	Day	21% 13% 4 7% 4 2 3 2 4 6% 32%	3596
	21st to end	Day	34% 13% 3 4 3 3 3 3 4 4 26%	4004
February	1st to 10th	Day	31% 18% 5% 6% 4 4 4 3 4 4 18%	1783
	11th to 20th	Day	27% 22% 3 7% 4 4 3 3 3 4 20%	1755
	21st to end	Day	22% 27% 5% 10% 5% 3 4 2 3 4 17%	1529
March	1st to 10th	Day	24% 22% 4 8% 4 4 3 2 3 5% 19%	3138
	11th to 20th	Day	21% 18% 3 6% 4 3 3 2 3 3 33%	3490
	21st to end	Day	29% 18% 4 9% 5% 5% 4 3 3 4 16%	4000
April	1st to 10th	Day	29% 22% 4 7% 5% 5% 4 3 4 5% 14%	2280
	11th to 20th	Day	26% 18% 4 9% 5% 4 4 3 4 4 19%	2261
	21st to end	Day	31% 17% 4 8% 5% 3 4 2 4 4 17%	2566
May	1st to 10th	Day	20% 15% 3 8% 5% 4 4 3 4 5% 30%	4420
	11th to 20th	Day	21% 10% 3 7% 5% 5% 4 4 5% 7% 29%	4377
	21st to end	Day	37% 12% 4 9% 6% 5% 4 3 4 4 14%	4813
June	1st to 10th	Day	33% 10% 2 7% 4 5% 4 3 4 5% 22%	2730
	11th to 20th	Day	35% 12% 4 9% 5% 4 4 3 4 4 15%	2850
	21st to end	Day	21% 9% 3 7% 6% 5% 4 4 5% 5% 32%	2850
July	1st to 10th	Day	10% 4 2 4 3 3 3 3 5% 5% 59%	4740
	11th to 20th	Day	8% 4 1 3 3 3 3 3 4 4 65%	4559
	21st to end	Day	14% 4 2 4 2 2 4 3 5% 7% 52%	4790
August	1st to 10th	Day	8% 4 2 3 2 2 3 3 5% 7% 61%	4401
	11th to 20th	Day	15% 8% 2 8% 4 4 4 4 6% 8% 37%	4064
	21st to end	Day	17% 8% 3 8% 5% 4 4 3 4 6% 38%	4314
September	1st to 10th	Day	15% 7% 3 5% 4 3 4 3 5% 6% 46%	2280
	11th to 20th	Day	20% 8% 2 6% 5% 4 4 3 4 5% 37%	2280
	21st to end	Day	27% 7% 3 5% 3 3 4 3 3 5% 37%	2021
October	1st to 10th	Day	20% 9% 3 6% 4 4 4 4 7% 8% 31%	3180
	11th to 20th	Day	34% 11% 2 6% 4 3 3 3 4 5% 25%	3161
	21st to end	Day	32% 13% 4 9% 4 5% 5% 3 4 5% 16%	3172
November	1st to 10th	Day	40% 13% 3 6% 4 3 4 4 4 3 15%	1616
	11th to 20th	Day	39% 17% 3 7% 4 3 2 2 3 3 19%	1600
	21st to end	Day	37% 18% 4 5% 3 3 3 2 3 5% 17%	1600
December	1st to 10th	Day	23% 13% 4 5% 4 4 4 3 5% 6% 30%	2620
	11th to 20th	Day	28% 24% 6% 10% 4 4 3 3 3 3 13%	3025
	21st to end	Day	32% 24% 5% 9% 4 5% 3 2 3 3 9%	3502
January	1st to 10th	Night	30% 23% 5% 9% 4 3 4 3 4 3 11%	6766
	11th to 20th	Night	22% 14% 4 7% 3 3 3 4 6% 7% 28%	6283
	21st to end	Night	30% 14% 3 5% 3 3 3 2 4 4 28%	6952
February	1st to 10th	Night	30% 20% 4 8% 5% 4 3 3 3 4 16%	2615
	11th to 20th	Night	26% 25% 4 7% 4 3 2 2 3 3 20%	2532
	21st to end	Night	28% 23% 3 8% 4 3 3 3 3 4 18%	2018
March	1st to 10th	Night	22% 23% 4 7% 4 3 4 2 4 5% 20%	3720
	11th to 20th	Night	23% 18% 2 5% 2 2 2 2 3 5% 35%	3489
	21st to end	Night	30% 22% 4 10% 4 3 3 2 3 3 16%	3652
April	1st to 10th	Night	27% 21% 3 7% 5% 4 4 3 4 5% 17%	1900
	11th to 20th	Night	27% 18% 3 7% 5% 4 4 3 4 4 22%	1868
	21st to end	Night	34% 14% 3 7% 5% 5% 3 2 3 4 20%	1612
May	1st to 10th	Night	19% 15% 3 6% 3 3 3 3 3 4 38%	2540
	11th to 20th	Night	19% 10% 3 7% 4 3 3 3 5% 8% 35%	2516
	21st to end	Night	36% 11% 4 8% 4 4 5% 3 4 5% 17%	2762
June	1st to 10th	Night	27% 10% 3 7% 4 4 5% 4 5% 6% 26%	1445
	11th to 20th	Night	27% 13% 3 7% 5% 4 4 4 5% 5% 23%	1330
	21st to end	Night	16% 8% 2 7% 4 4 5% 3 6% 6% 38%	1330
July	1st to 10th	Night	9% 5% 2 4 3 3 2 2 3 5% 63%	2220
	11th to 20th	Night	6% 3 1 3 3 2 2 2 3 4 71%	2398
	21st to end	Night	11% 3 2 4 3 3 3 3 4 6% 59%	2762
August	1st to 10th	Night	7% 2 1 3 2 3 3 3 5% 7% 65%	2529
	11th to 20th	Night	13% 7% 3 6% 3 4 4 3 5% 6% 46%	2769
	21st to end	Night	19% 6% 2 6% 4 3 4 3 4 6% 43%	3360
September	1st to 10th	Night	14% 7% 2 5% 3 4 4 3 4 6% 50%	1900
	11th to 20th	Night	22% 9% 3 6% 4 3 4 3 4 4 38%	1900
	21st to end	Night	26% 8% 2 6% 3 3 4 3 5% 5% 33%	2155
October	1st to 10th	Night	19% 8% 3 7% 4 4 5% 5% 7% 8% 30%	3800
	11th to 20th	Night	35% 10% 3 4 3 3 3 3 4 5% 28%	3777
	21st to end	Night	33% 16% 4 8% 4 3 3 3 4 4 18%	4387
November	1st to 10th	Night	40% 16% 3 6% 5% 4 4 2 3 4 14%	2678
	11th to 20th	Night	42% 15% 3 6% 3 3 2 2 4 4 17%	2800
	21st to end	Night	37% 17% 3 7% 3 3 3 2 3 3 17%	2800
December	1st to 10th	Night	21% 14% 3 7% 4 4 4 3 6% 7% 27%	4560
	11th to 20th	Night	32% 21% 4 9% 5% 3 3 2 4 3 12%	5180
	21st to end	Night	32% 25% 5% 9% 4 3 4 2 3 3 8%	7435

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	79% 4 5% 9% 2 1	3179
	11th to 20th	Day	53% 4 12% 18% 10% 2	3620
	21st to end	Day	62% 5% 5% 17% 11%	4004
February	1st to 10th	Day	70% 7% 7% 9% 7% 1	1783
	11th to 20th	Day	70% 5% 7% 9% 8% 1	1764
	21st to end	Day	73% 5% 6% 10% 4 1	1529
March	1st to 10th	Day	69% 5% 9% 10% 6%	3138
	11th to 20th	Day	59% 4 10% 25% 2	3490
	21st to end	Day	73% 7% 8% 9% 3	4000
April	1st to 10th	Day	75% 7% 10% 7% 1	2280
	11th to 20th	Day	70% 6% 8% 9% 6% 1	2261
	21st to end	Day	73% 6% 8% 8% 4 1	2566
May	1st to 10th	Day	58% 6% 14% 17% 6%	4420
	11th to 20th	Day	53% 12% 19% 14% 2	4380
	21st to end	Day	75% 8% 9% 7% 1	4814
June	1st to 10th	Day	65% 7% 13% 9% 6% 1	2730
	11th to 20th	Day	73% 7% 9% 9% 3	2850
	21st to end	Day	53% 9% 11% 19% 6% 1	2850
July	1st to 10th	Day	27% 6% 9% 23% 23% 12%	4666
	11th to 20th	Day	23% 5% 8% 29% 30% 4	4479
	21st to end	Day	30% 6% 16% 31% 13% 3	4639
August	1st to 10th	Day	23% 6% 13% 30% 26% 2	4384
	11th to 20th	Day	41% 10% 18% 20% 9% 2	4104
	21st to end	Day	47% 8% 11% 23% 11% 1	4313
September	1st to 10th	Day	40% 7% 11% 21% 15% 6%	2280
	11th to 20th	Day	48% 7% 9% 16% 16% 4	2280
	21st to end	Day	51% 7% 13% 15% 11% 3	2021
October	1st to 10th	Day	46% 10% 12% 25% 6%	3180
	11th to 20th	Day	62% 6% 9% 12% 10% 1	3161
	21st to end	Day	67% 8% 7% 9% 8%	3172
November	1st to 10th	Day	73% 7% 7% 8% 4	1616
	11th to 20th	Day	74% 4 5% 8% 7% 2	1600
	21st to end	Day	72% 4 5% 9% 8% 2	1600
December	1st to 10th	Day	57% 5% 9% 18% 11% 1	2620
	11th to 20th	Day	76% 5% 7% 9% 2	3028
	21st to end	Day	80% 5% 7% 5% 2	3502
January	1st to 10th	Night	76% 5% 6% 9% 3 1	6766
	11th to 20th	Night	53% 6% 13% 18% 9% 1	6321
	21st to end	Night	61% 4 10% 15% 9% 1	6952
February	1st to 10th	Night	73% 4 7% 9% 5% 1	2615
	11th to 20th	Night	70% 5% 7% 9% 7% 2	2534
	21st to end	Night	71% 5% 7% 11% 4	2018
March	1st to 10th	Night	65% 6% 11% 9% 8% 1	3720
	11th to 20th	Night	54% 6% 12% 25% 2	3490
	21st to end	Night	74% 7% 11% 8%	3652
April	1st to 10th	Night	71% 8% 11% 9% 1	1900
	11th to 20th	Night	66% 7% 10% 10% 6% 1	1868
	21st to end	Night	70% 7% 8% 9% 4	1612
May	1st to 10th	Night	51% 8% 15% 23% 4	2540
	11th to 20th	Night	48% 14% 19% 16% 3	2516
	21st to end	Night	70% 12% 10% 7%	2762
June	1st to 10th	Night	60% 9% 15% 11% 5% 1	1445
	11th to 20th	Night	63% 11% 13% 11% 2	1330
	21st to end	Night	46% 11% 17% 19% 6% 1	1330
July	1st to 10th	Night	27% 6% 9% 24% 25% 8%	2185
	11th to 20th	Night	19% 5% 10% 23% 38% 4	2355
	21st to end	Night	27% 7% 17% 26% 20% 3	2674
August	1st to 10th	Night	20% 6% 17% 34% 21% 2	2521
	11th to 20th	Night	35% 10% 24% 19% 10% 2	2795
	21st to end	Night	42% 7% 15% 25% 10% 1	3360
September	1st to 10th	Night	37% 7% 14% 23% 15% 4	1900
	11th to 20th	Night	51% 6% 9% 17% 14% 4	1900
	21st to end	Night	52% 7% 13% 16% 9% 2	2155
October	1st to 10th	Night	48% 9% 15% 22% 5%	3800
	11th to 20th	Night	59% 5% 10% 16% 9%	3777
	21st to end	Night	68% 6% 7% 10% 7%	4387
November	1st to 10th	Night	76% 6% 7% 7% 4 1	2678
	11th to 20th	Night	73% 5% 7% 8% 6% 2	2800
	21st to end	Night	74% 4 5% 8% 8% 2	2800
December	1st to 10th	Night	55% 6% 10% 18% 9% 1	4560
	11th to 20th	Night	76% 5% 6% 9% 3	5176
	21st to end	Night	81% 6% 5% 5% 2	7435

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	47% 13% 17% 16% 7% 1	200
	11th to 20th	Day	43% 10% 18% 20% 10% 1	200
	21st to end	Day	44% 7% 21% 20% 6% 1	220
February	1st to 10th	Day	43% 12% 26% 14% 4 1	383
	11th to 20th	Day	43% 14% 23% 15% 5% 1	395
	21st to end	Day	38% 14% 26% 17% 6%	359
March	1st to 10th	Day	38% 15% 24% 18% 5%	460
	11th to 20th	Day	35% 15% 20% 21% 8% 1	460
	21st to end	Day	43% 15% 21% 17% 4	506
April	1st to 10th	Day	43% 14% 20% 17% 6%	460
	11th to 20th	Day	35% 18% 24% 16% 7%	452
	21st to end	Day	42% 13% 23% 17% 5%	460
May	1st to 10th	Day	26% 16% 29% 24% 5%	463
	11th to 20th	Day	32% 10% 25% 22% 10% 1	488
	21st to end	Day	35% 13% 23% 19% 8% 2	529
June	1st to 10th	Day	31% 14% 26% 21% 7% 2	560
	11th to 20th	Day	35% 15% 28% 16% 5% 1	680
	21st to end	Day	23% 11% 27% 29% 10% 1	680
July	1st to 10th	Day	18% 9% 31% 32% 8% 1	671
	11th to 20th	Day	14% 10% 31% 30% 12% 3	566
	21st to end	Day	11% 8% 31% 31% 15% 5%	531
August	1st to 10th	Day	16% 5% 26% 32% 16% 4	487
	11th to 20th	Day	9% 8% 28% 34% 17% 4	477
	21st to end	Day	17% 12% 29% 26% 12% 3	539
September	1st to 10th	Day	19% 11% 29% 26% 11% 3	490
	11th to 20th	Day	24% 10% 25% 29% 11% 1	490
	21st to end	Day	28% 13% 25% 21% 11% 2	490
October	1st to 10th	Day	31% 8% 23% 20% 15% 2	490
	11th to 20th	Day	40% 8% 18% 20% 12% 2	490
	21st to end	Day	39% 12% 24% 15% 9% 1	377
November	1st to 10th	Day	40% 9% 28% 16% 6%	225
	11th to 20th	Day	48% 12% 16% 14% 8% 2	200
	21st to end	Day	46% 9% 22% 13% 10% 2	200
December	1st to 10th	Day	50% 6% 9% 15% 17% 4	200
	11th to 20th	Day	45% 13% 22% 15% 7%	200
	21st to end	Day	41% 14% 27% 14% 4	220
January	1st to 10th	Night	53% 8% 19% 18% 2	900
	11th to 20th	Night	43% 9% 24% 22% 2	800
	21st to end	Night	43% 8% 24% 21% 4	880
February	1st to 10th	Night	43% 10% 28% 16% 2	800
	11th to 20th	Night	41% 9% 29% 17% 5%	784
	21st to end	Night	42% 10% 26% 17% 4	646
March	1st to 10th	Night	37% 11% 23% 23% 7%	760
	11th to 20th	Night	42% 11% 20% 20% 7%	760
	21st to end	Night	44% 10% 25% 16% 5%	836
April	1st to 10th	Night	39% 9% 21% 24% 7%	760
	11th to 20th	Night	38% 9% 26% 21% 6%	740
	21st to end	Night	43% 5% 26% 22% 5%	472
May	1st to 10th	Night	26% 8% 26% 31% 8%	380
	11th to 20th	Night	25% 5% 21% 36% 13%	374
	21st to end	Night	32% 5% 21% 29% 13%	411
June	1st to 10th	Night	31% 7% 19% 30% 13%	380
	11th to 20th	Night	33% 5% 25% 24% 13%	380
	21st to end	Night	18% 4 26% 35% 17%	380
July	1st to 10th	Night	15% 4 19% 36% 24% 1	370
	11th to 20th	Night	13% 5% 14% 38% 29% 1	368
	21st to end	Night	10% 2 15% 33% 38% 1	416
August	1st to 10th	Night	13% 2 10% 31% 44% 1	378
	11th to 20th	Night	11% 2 10% 39% 37% 1	533
	21st to end	Night	18% 3 16% 40% 23%	750
September	1st to 10th	Night	17% 4 21% 37% 20%	760
	11th to 20th	Night	26% 4 19% 29% 21%	760
	21st to end	Night	32% 3 19% 34% 13%	760
October	1st to 10th	Night	30% 4 24% 29% 14%	760
	11th to 20th	Night	39% 7% 19% 27% 7%	760
	21st to end	Night	43% 9% 25% 19% 5%	836
November	1st to 10th	Night	49% 8% 25% 18% 1	780
	11th to 20th	Night	52% 10% 18% 16% 4	800
	21st to end	Night	47% 10% 21% 17% 5%	800
December	1st to 10th	Night	36% 8% 31% 20% 5%	800
	11th to 20th	Night	50% 12% 24% 13% 2	800
	21st to end	Night	52% 11% 23% 12% 1	985

Page generated at 2025-02-22 03:51:35. Version ac07

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