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 2024-02-15.

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	28% 13% 4 6% 5% 3 4 3 4 5% 27%	78173
	Night	30% 14% 3 6% 4 2 3 3 4 5% 25%	80814
Transparency	Day	61% 6% 10% 14% 7% 1	77890
	Night	64% 6% 10% 13% 6% 1	80677
Seeing	Day	32% 11% 25% 22% 9% 1	13981
	Night	37% 7% 22% 24% 10%	22570

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	38% 24% 5% 7% 4 3 3 2 2 3 10%	2219
	11th to 20th	Day	29% 13% 5% 7% 5% 2 3 2 3 6% 24%	2496
	21st to end	Day	48% 16% 4 4 4 2 2 2 3 4 11%	2794
February	1st to 10th	Day	33% 17% 5% 5% 4 2 4 3 3 5% 17%	1693
	11th to 20th	Day	28% 21% 4 6% 4 3 3 4 3 5% 20%	1612
	21st to end	Day	22% 26% 5% 9% 6% 2 4 3 3 4 17%	1406
March	1st to 10th	Day	30% 20% 4 6% 5% 3 3 2 3 5% 18%	1800
	11th to 20th	Day	33% 19% 4 6% 6% 3 4 3 3 3 16%	1980
	21st to end	Day	32% 18% 4 8% 7% 3 5% 4 3 4 12%	2276
April	1st to 10th	Day	30% 20% 4 6% 5% 3 5% 4 4 5% 14%	2160
	11th to 20th	Day	28% 16% 5% 8% 6% 3 5% 3 4 4 17%	2140
	21st to end	Day	31% 17% 4 7% 7% 2 4 3 3 4 17%	2430
May	1st to 10th	Day	23% 14% 3 7% 7% 3 5% 4 4 5% 24%	2520
	11th to 20th	Day	24% 10% 4 7% 6% 3 5% 5% 5% 6% 25%	2477
	21st to end	Day	32% 10% 4 7% 6% 4 4 3 4 4 21%	2723
June	1st to 10th	Day	33% 10% 3 6% 5% 4 4 4 4 5% 23%	2586
	11th to 20th	Day	37% 11% 4 8% 6% 3 4 4 4 5% 15%	2700
	21st to end	Day	21% 8% 4 6% 7% 3 4 5% 4 5% 32%	2700
July	1st to 10th	Day	17% 6% 3 4 5% 3 4 4 5% 6% 43%	2700
	11th to 20th	Day	15% 6% 2 4 4 2 4 5% 5% 5% 47%	2603
	21st to end	Day	12% 5% 2 4 3 2 3 3 4 6% 57%	2741
August	1st to 10th	Day	15% 6% 2 4 4 2 3 3 4 6% 51%	2507
	11th to 20th	Day	11% 5% 2 4 3 2 4 4 5% 8% 53%	2324
	21st to end	Day	17% 6% 2 6% 5% 3 3 4 4 7% 42%	2458
September	1st to 10th	Day	16% 7% 3 4 5% 2 3 3 5% 6% 46%	2160
	11th to 20th	Day	20% 7% 3 5% 5% 3 4 4 4 5% 39%	2160
	21st to end	Day	28% 7% 3 4 4 2 3 3 3 5% 37%	1916
October	1st to 10th	Day	26% 10% 3 5% 4 2 3 4 4 7% 33%	1800
	11th to 20th	Day	32% 11% 2 5% 4 2 3 3 4 6% 28%	1800
	21st to end	Day	38% 11% 3 5% 5% 3 3 2 2 4 24%	1827
November	1st to 10th	Day	42% 12% 3 5% 5% 2 3 5% 5% 3 15%	1534
	11th to 20th	Day	41% 15% 3 6% 4 3 2 2 3 3 20%	1520
	21st to end	Day	39% 16% 4 4 3 2 4 3 3 5% 18%	1520
December	1st to 10th	Day	32% 15% 4 5% 5% 2 3 2 4 4 24%	1520
	11th to 20th	Day	33% 18% 4 6% 4 2 3 3 3 4 20%	1925
	21st to end	Day	32% 20% 6% 8% 6% 3 3 2 4 4 12%	2446
January	1st to 10th	Night	37% 24% 5% 6% 5% 3 3 2 2 2 11%	4726
	11th to 20th	Night	32% 14% 4 7% 4 2 2 3 3 7% 22%	4383
	21st to end	Night	43% 17% 3 6% 5% 2 2 2 2 4 13%	4862
February	1st to 10th	Night	32% 19% 5% 7% 5% 3 4 3 4 4 15%	2485
	11th to 20th	Night	28% 24% 4 6% 5% 2 2 2 3 3 19%	2329
	21st to end	Night	27% 22% 4 7% 5% 3 3 4 3 4 19%	1849
March	1st to 10th	Night	31% 15% 4 5% 5% 3 4 3 4 5% 22%	2157
	11th to 20th	Night	33% 18% 3 6% 4 3 3 4 4 5% 18%	1979
	21st to end	Night	34% 18% 3 7% 5% 2 4 3 4 4 15%	2079
April	1st to 10th	Night	27% 21% 3 6% 5% 3 4 4 5% 5% 18%	1800
	11th to 20th	Night	28% 17% 4 6% 6% 2 4 4 4 4 21%	1769
	21st to end	Night	34% 14% 3 6% 5% 4 4 3 3 4 21%	1528
May	1st to 10th	Night	23% 11% 4 6% 5% 3 4 5% 5% 4 30%	1440
	11th to 20th	Night	23% 9% 4 7% 5% 3 4 5% 6% 8% 26%	1416
	21st to end	Night	29% 9% 3 6% 4 3 4 5% 5% 7% 25%	1552
June	1st to 10th	Night	27% 9% 3 6% 5% 3 5% 5% 4 6% 27%	1369
	11th to 20th	Night	28% 12% 4 6% 6% 3 3 4 5% 6% 23%	1260
	21st to end	Night	16% 6% 3 5% 4 3 5% 5% 5% 7% 40%	1260
July	1st to 10th	Night	14% 6% 2 5% 5% 3 4 3 4 7% 46%	1260
	11th to 20th	Night	11% 5% 2 4 5% 2 3 3 5% 6% 53%	1354
	21st to end	Night	10% 3 2 3 2 2 2 3 4 6% 63%	1576
August	1st to 10th	Night	11% 3 2 3 3 2 3 3 5% 6% 58%	1432
	11th to 20th	Night	8% 4 2 3 3 2 3 4 4 6% 61%	1572
	21st to end	Night	14% 5% 2 5% 4 2 4 4 4 8% 47%	1898
September	1st to 10th	Night	14% 7% 2 4 4 3 3 4 4 6% 50%	1800
	11th to 20th	Night	23% 8% 3 5% 5% 2 3 4 3 4 40%	1800
	21st to end	Night	26% 8% 2 5% 4 2 4 4 5% 6% 34%	2040
October	1st to 10th	Night	26% 8% 3 6% 5% 2 4 4 4 5% 33%	2160
	11th to 20th	Night	34% 10% 3 5% 4 2 4 3 3 4 28%	2160
	21st to end	Night	36% 11% 3 5% 4 3 3 4 3 4 23%	2528
November	1st to 10th	Night	41% 15% 4 5% 5% 3 4 3 3 4 14%	2540
	11th to 20th	Night	43% 13% 3 5% 4 2 2 2 3 5% 17%	2660
	21st to end	Night	40% 15% 4 6% 4 2 3 3 3 4 18%	2660
December	1st to 10th	Night	30% 15% 3 5% 4 2 3 4 5% 5% 23%	2660
	11th to 20th	Night	37% 18% 4 7% 5% 2 3 3 4 4 15%	3280
	21st to end	Night	33% 21% 5% 7% 5% 3 4 4 3 4 11%	5191

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 4 7% 2 1	2219
	11th to 20th	Day	65% 4 9% 12% 7% 3	2520
	21st to end	Day	79% 4 5% 7% 4	2794
February	1st to 10th	Day	72% 6% 7% 9% 6% 1	1693
	11th to 20th	Day	70% 5% 7% 9% 8% 1	1621
	21st to end	Day	72% 6% 6% 11% 5% 1	1406
March	1st to 10th	Day	73% 4 8% 10% 4 1	1800
	11th to 20th	Day	75% 6% 7% 9% 3	1980
	21st to end	Day	79% 6% 7% 7% 1	2276
April	1st to 10th	Day	75% 7% 10% 7% 1	2160
	11th to 20th	Day	72% 6% 7% 9% 6% 1	2140
	21st to end	Day	73% 6% 8% 8% 4 1	2430
May	1st to 10th	Day	64% 8% 12% 12% 4	2520
	11th to 20th	Day	60% 9% 15% 13% 3	2480
	21st to end	Day	68% 7% 11% 12% 1	2724
June	1st to 10th	Day	66% 7% 13% 9% 6% 1	2586
	11th to 20th	Day	74% 7% 8% 8% 2	2700
	21st to end	Day	53% 9% 11% 19% 6% 1	2700
July	1st to 10th	Day	43% 8% 13% 24% 11% 2	2626
	11th to 20th	Day	38% 7% 12% 29% 12% 1	2523
	21st to end	Day	30% 5% 12% 33% 15% 5%	2589
August	1st to 10th	Day	35% 8% 16% 23% 15% 3	2490
	11th to 20th	Day	29% 8% 18% 27% 15% 3	2324
	21st to end	Day	43% 8% 14% 26% 9% 1	2458
September	1st to 10th	Day	41% 6% 10% 22% 15% 6%	2160
	11th to 20th	Day	48% 7% 9% 16% 16% 4	2160
	21st to end	Day	52% 7% 12% 15% 12% 3	1916
October	1st to 10th	Day	52% 7% 13% 18% 9% 1	1800
	11th to 20th	Day	59% 6% 10% 15% 9% 1	1800
	21st to end	Day	67% 4 7% 12% 10%	1827
November	1st to 10th	Day	74% 7% 6% 8% 4 1	1534
	11th to 20th	Day	74% 4 4 9% 7% 2	1520
	21st to end	Day	72% 3 5% 9% 8% 2	1520
December	1st to 10th	Day	68% 5% 7% 11% 9% 1	1520
	11th to 20th	Day	69% 5% 10% 12% 3 1	1928
	21st to end	Day	77% 6% 7% 7% 3	2446
January	1st to 10th	Night	82% 4 3 8% 2 1	4726
	11th to 20th	Night	64% 5% 8% 14% 8% 2	4421
	21st to end	Night	79% 4 5% 7% 4 1	4862
February	1st to 10th	Night	74% 4 8% 9% 4 1	2485
	11th to 20th	Night	72% 5% 7% 9% 6% 2	2331
	21st to end	Night	70% 5% 8% 12% 5%	1849
March	1st to 10th	Night	66% 6% 13% 10% 5%	2157
	11th to 20th	Night	70% 6% 9% 11% 4	1980
	21st to end	Night	73% 8% 11% 7%	2079
April	1st to 10th	Night	71% 8% 11% 9% 1	1800
	11th to 20th	Night	67% 7% 10% 10% 5% 1	1769
	21st to end	Night	70% 7% 8% 10% 5% 1	1528
May	1st to 10th	Night	56% 11% 13% 16% 3	1440
	11th to 20th	Night	58% 10% 15% 12% 4	1416
	21st to end	Night	60% 10% 16% 13% 1	1552
June	1st to 10th	Night	59% 9% 15% 12% 4 1	1369
	11th to 20th	Night	64% 11% 13% 11% 2	1260
	21st to end	Night	45% 12% 17% 19% 6% 1	1260
July	1st to 10th	Night	41% 10% 15% 20% 11% 2	1225
	11th to 20th	Night	34% 9% 17% 26% 12% 1	1311
	21st to end	Night	22% 8% 14% 34% 18% 4	1488
August	1st to 10th	Night	29% 8% 19% 27% 15% 3	1424
	11th to 20th	Night	25% 8% 22% 25% 17% 3	1572
	21st to end	Night	37% 7% 18% 27% 9% 1	1898
September	1st to 10th	Night	38% 7% 13% 24% 14% 4	1800
	11th to 20th	Night	50% 5% 9% 17% 15% 4	1800
	21st to end	Night	53% 7% 12% 17% 10% 3	2040
October	1st to 10th	Night	55% 5% 12% 19% 8%	2160
	11th to 20th	Night	61% 6% 9% 14% 9% 1	2160
	21st to end	Night	66% 5% 7% 13% 9%	2528
November	1st to 10th	Night	76% 5% 7% 7% 4 1	2540
	11th to 20th	Night	72% 4 7% 8% 6% 2	2660
	21st to end	Night	73% 4 5% 8% 9% 2	2660
December	1st to 10th	Night	63% 6% 9% 13% 8% 1	2660
	11th to 20th	Night	75% 6% 6% 9% 4	3276
	21st to end	Night	77% 7% 6% 7% 3	5191

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	48% 12% 17% 15% 8% 1	180
	11th to 20th	Day	47% 9% 17% 19% 8% 1	180
	21st to end	Day	47% 8% 20% 21% 5%	198
February	1st to 10th	Day	46% 11% 26% 13% 4	353
	11th to 20th	Day	45% 13% 22% 15% 5% 1	348
	21st to end	Day	35% 14% 26% 18% 6%	314
March	1st to 10th	Day	39% 15% 24% 18% 5%	420
	11th to 20th	Day	37% 15% 20% 20% 6% 1	420
	21st to end	Day	44% 15% 21% 16% 4	462
April	1st to 10th	Day	44% 13% 20% 16% 7%	420
	11th to 20th	Day	37% 17% 23% 16% 8%	412
	21st to end	Day	41% 13% 24% 17% 5%	420
May	1st to 10th	Day	26% 16% 30% 23% 4	423
	11th to 20th	Day	33% 9% 24% 23% 10% 1	448
	21st to end	Day	33% 12% 25% 20% 8% 2	485
June	1st to 10th	Day	30% 15% 26% 21% 6% 2	516
	11th to 20th	Day	36% 15% 28% 16% 4 1	630
	21st to end	Day	22% 11% 27% 29% 10% 1	630
July	1st to 10th	Day	19% 9% 32% 32% 8% 1	621
	11th to 20th	Day	16% 11% 32% 29% 10% 2	522
	21st to end	Day	10% 8% 32% 31% 14% 5%	487
August	1st to 10th	Day	18% 6% 26% 32% 15% 4	447
	11th to 20th	Day	9% 7% 28% 34% 18% 4	437
	21st to end	Day	17% 12% 30% 27% 12% 2	495
September	1st to 10th	Day	21% 11% 31% 26% 10% 1	450
	11th to 20th	Day	26% 8% 24% 30% 11% 1	450
	21st to end	Day	29% 12% 26% 21% 11% 2	450
October	1st to 10th	Day	32% 8% 23% 20% 14% 2	450
	11th to 20th	Day	40% 8% 18% 20% 12% 2	450
	21st to end	Day	40% 11% 23% 15% 9% 1	342
November	1st to 10th	Day	41% 8% 29% 17% 6%	203
	11th to 20th	Day	48% 11% 16% 14% 9% 2	180
	21st to end	Day	49% 7% 23% 10% 9% 2	180
December	1st to 10th	Day	54% 6% 10% 14% 13% 3	180
	11th to 20th	Day	45% 9% 23% 16% 7%	180
	21st to end	Day	43% 11% 28% 14% 5%	198
January	1st to 10th	Night	56% 8% 17% 18% 2	850
	11th to 20th	Night	45% 9% 23% 20% 2	760
	21st to end	Night	45% 8% 24% 20% 3	836
February	1st to 10th	Night	45% 10% 28% 16% 2	760
	11th to 20th	Night	42% 8% 27% 18% 5%	722
	21st to end	Night	40% 10% 27% 19% 4	592
March	1st to 10th	Night	38% 10% 22% 23% 6%	720
	11th to 20th	Night	44% 12% 21% 18% 6%	720
	21st to end	Night	44% 10% 25% 16% 5%	792
April	1st to 10th	Night	40% 8% 22% 23% 7%	720
	11th to 20th	Night	39% 8% 25% 21% 6%	701
	21st to end	Night	42% 4 26% 22% 5%	448
May	1st to 10th	Night	27% 8% 26% 31% 8%	360
	11th to 20th	Night	25% 5% 20% 37% 13%	354
	21st to end	Night	31% 4 22% 30% 13%	389
June	1st to 10th	Night	31% 7% 19% 30% 13%	360
	11th to 20th	Night	34% 4 25% 24% 13%	360
	21st to end	Night	18% 3 26% 34% 18%	360
July	1st to 10th	Night	16% 4 19% 35% 25% 1	350
	11th to 20th	Night	13% 6% 15% 39% 26% 1	348
	21st to end	Night	10% 2 15% 34% 39% 1	394
August	1st to 10th	Night	14% 2 10% 31% 43% 1	358
	11th to 20th	Night	11% 2 10% 41% 37%	504
	21st to end	Night	18% 3 16% 40% 22%	710
September	1st to 10th	Night	18% 4 22% 37% 19%	720
	11th to 20th	Night	26% 4 20% 29% 21%	720
	21st to end	Night	32% 2 19% 35% 12%	720
October	1st to 10th	Night	31% 3 24% 28% 14%	720
	11th to 20th	Night	39% 7% 19% 27% 8%	720
	21st to end	Night	43% 8% 25% 19% 5%	792
November	1st to 10th	Night	50% 6% 25% 17% 1	740
	11th to 20th	Night	52% 9% 19% 16% 4	760
	21st to end	Night	48% 9% 21% 16% 5%	760
December	1st to 10th	Night	37% 8% 31% 18% 4	760
	11th to 20th	Night	50% 12% 24% 13% 1	760
	21st to end	Night	53% 10% 24% 13% 1	930

Page generated at 2024-02-12 03:35:37. Version ac07

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