Skymont Scout Reservation
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Skymont Scout Reservation clear sky chart from 2005-11-06 to 2026-05-02.

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	14% 8% 3 7% 5% 5% 5% 4 6% 7% 37%	131798
	Night	14% 9% 3 7% 4 4 4 3 5% 7% 40%	130719
Transparency	Day	43% 7% 11% 20% 15% 4	135523
	Night	41% 6% 11% 20% 17% 5%	135065
Seeing	Day	18% 13% 24% 21% 15% 7%	16513
	Night	18% 11% 23% 27% 18% 3	26586

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	19% 11% 6% 9% 5% 3 4 3 4 5% 31%	5258
	11th to 20th	Day	14% 8% 4 12% 3 2 3 2 3 4 45%	5280
	21st to end	Day	21% 9% 5% 8% 5% 4 4 3 4 6% 33%	6229
February	1st to 10th	Day	19% 12% 4 8% 4 3 3 3 4 5% 34%	2100
	11th to 20th	Day	21% 10% 4 8% 5% 4 3 3 4 4 33%	2048
	21st to end	Day	20% 9% 4 8% 5% 4 4 3 4 5% 35%	1730
March	1st to 10th	Day	18% 11% 3 7% 5% 4 4 4 5% 6% 33%	4580
	11th to 20th	Day	13% 9% 3 7% 4 4 3 3 5% 6% 45%	4990
	21st to end	Day	14% 9% 3 7% 4 4 4 4 5% 7% 40%	5691
April	1st to 10th	Day	13% 7% 2 5% 5% 4 5% 4 6% 7% 41%	2520
	11th to 20th	Day	13% 8% 3 5% 4 4 3 3 5% 6% 44%	2494
	21st to end	Day	14% 8% 2 7% 4 4 4 3 6% 8% 38%	2608
May	1st to 10th	Day	20% 9% 2 6% 5% 4 5% 5% 7% 8% 28%	5875
	11th to 20th	Day	16% 10% 4 10% 6% 5% 6% 4 5% 7% 26%	5861
	21st to end	Day	17% 8% 3 7% 4 5% 4 4 5% 7% 35%	6433
June	1st to 10th	Day	10% 6% 3 7% 5% 5% 6% 5% 7% 9% 36%	2600
	11th to 20th	Day	6% 5% 2 6% 5% 6% 7% 5% 6% 11% 41%	2600
	21st to end	Day	6% 5% 2 6% 6% 6% 6% 5% 8% 12% 37%	2600
July	1st to 10th	Day	7% 6% 2 6% 6% 6% 7% 5% 7% 11% 36%	5900
	11th to 20th	Day	10% 6% 2 7% 6% 7% 8% 6% 8% 11% 30%	5900
	21st to end	Day	13% 8% 3 8% 7% 7% 7% 6% 9% 11% 21%	6424
August	1st to 10th	Day	7% 5% 2 5% 5% 5% 6% 5% 9% 11% 42%	4118
	11th to 20th	Day	7% 5% 2 7% 6% 6% 7% 6% 7% 10% 37%	3849
	21st to end	Day	7% 4 2 6% 5% 6% 7% 5% 7% 9% 42%	4312
September	1st to 10th	Day	13% 6% 2 6% 5% 5% 6% 5% 5% 8% 38%	2315
	11th to 20th	Day	12% 6% 3 7% 5% 5% 5% 4 7% 7% 40%	2200
	21st to end	Day	13% 5% 2 6% 5% 4 5% 4 6% 7% 44%	2200
October	1st to 10th	Day	10% 5% 2 4 4 4 4 3 4 5% 54%	2200
	11th to 20th	Day	12% 5% 2 4 3 4 3 2 5% 7% 54%	2170
	21st to end	Day	14% 8% 2 5% 3 3 3 3 5% 6% 47%	2033
November	1st to 10th	Day	11% 6% 2 5% 4 3 4 3 5% 4 53%	1852
	11th to 20th	Day	13% 8% 2 6% 4 3 4 3 4 6% 47%	1890
	21st to end	Day	15% 10% 2 6% 4 3 4 3 5% 6% 42%	1890
December	1st to 10th	Day	16% 10% 3 6% 5% 4 4 3 4 4 42%	3020
	11th to 20th	Day	16% 14% 6% 10% 5% 4 4 3 4 4 30%	3463
	21st to end	Day	16% 13% 6% 8% 4 3 4 3 6% 8% 28%	4565
January	1st to 10th	Night	17% 13% 3 8% 3 3 3 3 4 5% 39%	7635
	11th to 20th	Night	16% 11% 4 7% 4 3 2 2 3 3 44%	7680
	21st to end	Night	20% 11% 4 7% 5% 3 3 2 3 4 37%	7948
February	1st to 10th	Night	18% 12% 3 8% 5% 3 4 3 5% 5% 35%	2520
	11th to 20th	Night	22% 11% 4 8% 4 4 4 3 3 4 33%	2458
	21st to end	Night	21% 11% 3 8% 3 4 3 3 5% 5% 33%	2076
March	1st to 10th	Night	18% 15% 3 6% 4 4 4 3 5% 7% 29%	5493
	11th to 20th	Night	13% 8% 2 4 4 4 4 4 6% 6% 46%	5189
	21st to end	Night	14% 9% 3 8% 5% 5% 4 3 4 5% 40%	5510
April	1st to 10th	Night	13% 6% 2 6% 4 4 3 4 7% 8% 44%	2100
	11th to 20th	Night	15% 6% 2 4 3 3 3 3 5% 7% 49%	2075
	21st to end	Night	14% 6% 2 6% 5% 4 4 4 6% 6% 44%	2011
May	1st to 10th	Night	14% 10% 3 8% 6% 5% 5% 4 6% 7% 32%	4042
	11th to 20th	Night	16% 12% 4 9% 6% 5% 5% 4 5% 7% 28%	4032
	21st to end	Night	15% 8% 2 6% 4 5% 5% 4 6% 9% 36%	4421
June	1st to 10th	Night	7% 8% 3 6% 4 5% 5% 5% 7% 10% 41%	1800
	11th to 20th	Night	5% 3 1 4 3 5% 4 4 8% 10% 52%	1800
	21st to end	Night	5% 4 2 7% 4 6% 4 5% 6% 11% 46%	1800
July	1st to 10th	Night	9% 6% 2 6% 5% 5% 5% 5% 7% 10% 40%	4058
	11th to 20th	Night	9% 6% 2 6% 4 4 5% 5% 8% 14% 37%	4057
	21st to end	Night	11% 8% 3 9% 5% 5% 6% 4 8% 11% 30%	4427
August	1st to 10th	Night	4 4 1 5% 4 4 4 4 7% 11% 52%	3013
	11th to 20th	Night	6% 5% 2 6% 4 4 4 4 7% 10% 46%	3200
	21st to end	Night	6% 4 2 4 4 4 5% 4 6% 9% 54%	3586
September	1st to 10th	Night	10% 6% 2 6% 3 4 4 4 7% 8% 46%	2064
	11th to 20th	Night	10% 5% 2 6% 4 5% 5% 4 6% 7% 46%	2200
	21st to end	Night	9% 6% 2 5% 4 4 4 3 5% 8% 50%	2200
October	1st to 10th	Night	10% 5% 2 5% 3 3 3 3 4 6% 58%	2200
	11th to 20th	Night	14% 5% 2 5% 3 3 3 3 5% 5% 53%	2230
	21st to end	Night	14% 8% 2 5% 3 3 3 2 5% 5% 50%	2803
November	1st to 10th	Night	13% 7% 2 5% 4 3 3 3 5% 6% 50%	2666
	11th to 20th	Night	12% 9% 2 5% 4 3 2 4 5% 7% 47%	2730
	21st to end	Night	15% 10% 4 6% 3 3 4 3 5% 5% 41%	2730
December	1st to 10th	Night	18% 12% 3 7% 4 3 4 3 4 4 38%	4380
	11th to 20th	Night	20% 13% 4 7% 4 3 3 2 4 4 36%	4952
	21st to end	Night	14% 15% 6% 9% 5% 4 4 3 5% 6% 29%	6633

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% 5% 9% 18% 12% 2	5259
	11th to 20th	Day	44% 3 4 15% 31% 3	5280
	21st to end	Day	53% 3 7% 20% 12% 5%	6229
February	1st to 10th	Day	54% 3 7% 17% 17% 2	2100
	11th to 20th	Day	55% 4 7% 16% 14% 4	2058
	21st to end	Day	51% 5% 7% 15% 18% 5%	1730
March	1st to 10th	Day	50% 6% 8% 11% 16% 8%	4580
	11th to 20th	Day	40% 5% 7% 19% 20% 10%	4990
	21st to end	Day	43% 5% 10% 25% 15% 1	5693
April	1st to 10th	Day	39% 8% 11% 23% 16% 3	2520
	11th to 20th	Day	40% 6% 8% 19% 24% 4	2494
	21st to end	Day	43% 7% 10% 24% 15% 1	2608
May	1st to 10th	Day	48% 10% 13% 20% 8% 1	5910
	11th to 20th	Day	54% 9% 13% 17% 7%	5865
	21st to end	Day	46% 8% 9% 20% 14% 2	6447
June	1st to 10th	Day	40% 11% 14% 21% 13% 1	2600
	11th to 20th	Day	34% 12% 17% 21% 15% 2	2600
	21st to end	Day	37% 12% 18% 17% 13% 3	2600
July	1st to 10th	Day	37% 10% 18% 24% 10% 1	5835
	11th to 20th	Day	42% 13% 21% 19% 4 1	5831
	21st to end	Day	51% 12% 18% 15% 3	6240
August	1st to 10th	Day	31% 10% 16% 30% 12% 1	4105
	11th to 20th	Day	38% 8% 16% 24% 13% 1	3885
	21st to end	Day	33% 11% 13% 27% 15% 1	4311
September	1st to 10th	Day	41% 11% 13% 17% 15% 5%	2315
	11th to 20th	Day	41% 9% 10% 19% 19% 2	2200
	21st to end	Day	39% 7% 12% 19% 18% 5%	2200
October	1st to 10th	Day	25% 4 7% 16% 35% 13%	3590
	11th to 20th	Day	22% 4 6% 22% 29% 17%	3514
	21st to end	Day	28% 5% 7% 24% 25% 10%	3257
November	1st to 10th	Day	33% 5% 9% 19% 27% 6%	1852
	11th to 20th	Day	38% 4 7% 22% 22% 7%	1890
	21st to end	Day	42% 4 8% 21% 21% 4	1890
December	1st to 10th	Day	46% 4 5% 20% 22% 3	3020
	11th to 20th	Day	57% 5% 7% 16% 13% 3	3460
	21st to end	Day	51% 6% 11% 20% 10% 2	4565
January	1st to 10th	Night	47% 4 14% 18% 15% 2	7636
	11th to 20th	Night	46% 3 5% 15% 26% 5%	7680
	21st to end	Night	53% 3 7% 14% 17% 7%	7948
February	1st to 10th	Night	51% 4 9% 17% 16% 3	2520
	11th to 20th	Night	56% 4 5% 16% 14% 5%	2459
	21st to end	Night	53% 5% 7% 15% 15% 5%	2076
March	1st to 10th	Night	53% 6% 7% 12% 17% 4	5493
	11th to 20th	Night	37% 6% 7% 19% 19% 13%	5189
	21st to end	Night	46% 5% 9% 23% 15% 2	5510
April	1st to 10th	Night	36% 7% 13% 21% 20% 3	2100
	11th to 20th	Night	34% 5% 10% 22% 23% 7%	2075
	21st to end	Night	39% 7% 12% 25% 16% 2	2011
May	1st to 10th	Night	49% 9% 14% 18% 9% 1	4069
	11th to 20th	Night	54% 9% 13% 15% 9%	4033
	21st to end	Night	41% 11% 13% 22% 12% 1	4429
June	1st to 10th	Night	37% 10% 15% 24% 13% 2	1800
	11th to 20th	Night	24% 9% 19% 31% 15% 2	1800
	21st to end	Night	30% 10% 17% 25% 14% 4	1800
July	1st to 10th	Night	35% 11% 19% 22% 11% 2	4015
	11th to 20th	Night	34% 11% 27% 22% 5% 2	4006
	21st to end	Night	45% 10% 22% 18% 4 1	4297
August	1st to 10th	Night	25% 8% 14% 36% 16% 1	3002
	11th to 20th	Night	30% 9% 23% 24% 13% 1	3230
	21st to end	Night	26% 9% 14% 30% 21% 1	3586
September	1st to 10th	Night	34% 9% 17% 19% 16% 5%	2064
	11th to 20th	Night	36% 8% 11% 21% 22% 2	2200
	21st to end	Night	32% 8% 11% 23% 21% 6%	2200
October	1st to 10th	Night	22% 3 7% 22% 29% 16%	3590
	11th to 20th	Night	22% 4 6% 21% 29% 19%	3625
	21st to end	Night	25% 3 6% 25% 29% 11%	4529
November	1st to 10th	Night	35% 5% 8% 21% 24% 8%	2666
	11th to 20th	Night	35% 4 8% 19% 25% 8%	2730
	21st to end	Night	44% 4 6% 20% 21% 5%	2730
December	1st to 10th	Night	50% 3 6% 15% 24% 3	4380
	11th to 20th	Night	51% 5% 6% 16% 20% 3	4954
	21st to end	Night	53% 6% 10% 20% 10% 1	6633

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	27% 26% 31% 13% 2	330
	11th to 20th	Day	34% 27% 25% 11% 2 1	330
	21st to end	Day	27% 29% 33% 8% 2	363
February	1st to 10th	Day	29% 28% 30% 12% 2	330
	11th to 20th	Day	41% 25% 26% 6% 1 1	330
	21st to end	Day	37% 26% 28% 8% 1	273
March	1st to 10th	Day	30% 23% 34% 11% 2	330
	11th to 20th	Day	27% 25% 29% 15% 4 1	492
	21st to end	Day	26% 20% 35% 13% 6%	594
April	1st to 10th	Day	20% 23% 28% 20% 9%	540
	11th to 20th	Day	20% 19% 32% 19% 9% 1	532
	21st to end	Day	21% 16% 30% 20% 11% 2	540
May	1st to 10th	Day	18% 16% 31% 20% 10% 5%	507
	11th to 20th	Day	16% 12% 26% 22% 16% 8%	527
	21st to end	Day	15% 7% 23% 29% 13% 13%	573
June	1st to 10th	Day	12% 7% 24% 24% 21% 13%	530
	11th to 20th	Day	8% 5% 15% 29% 26% 17%	530
	21st to end	Day	9% 4 20% 28% 23% 17%	530
July	1st to 10th	Day	10% 3 14% 30% 23% 19%	525
	11th to 20th	Day	9% 5% 11% 23% 29% 22%	524
	21st to end	Day	11% 2 11% 26% 30% 20%	576
August	1st to 10th	Day	13% 4 13% 26% 26% 16%	526
	11th to 20th	Day	10% 4 15% 30% 29% 12%	519
	21st to end	Day	13% 3 10% 23% 34% 16%	583
September	1st to 10th	Day	12% 5% 14% 26% 30% 14%	530
	11th to 20th	Day	12% 5% 16% 26% 26% 14%	530
	21st to end	Day	17% 6% 17% 27% 26% 6%	530
October	1st to 10th	Day	12% 6% 23% 32% 20% 7%	530
	11th to 20th	Day	13% 11% 31% 27% 15% 3	530
	21st to end	Day	22% 11% 30% 25% 11% 2	416
November	1st to 10th	Day	18% 14% 32% 25% 9% 2	330
	11th to 20th	Day	15% 21% 39% 20% 4	330
	21st to end	Day	23% 22% 32% 14% 8% 1	330
December	1st to 10th	Day	30% 21% 31% 15% 3	330
	11th to 20th	Day	26% 22% 30% 15% 6%	330
	21st to end	Day	26% 25% 33% 12% 4	363
January	1st to 10th	Night	25% 19% 34% 19% 3	840
	11th to 20th	Night	28% 22% 28% 18% 4	840
	21st to end	Night	22% 19% 36% 22% 2	924
February	1st to 10th	Night	24% 17% 32% 23% 3	840
	11th to 20th	Night	32% 18% 30% 17% 2	823
	21st to end	Night	29% 19% 31% 19% 2	692
March	1st to 10th	Night	22% 18% 32% 25% 4	840
	11th to 20th	Night	22% 16% 32% 23% 6% 1	840
	21st to end	Night	21% 15% 31% 23% 9%	897
April	1st to 10th	Night	16% 17% 28% 29% 10%	630
	11th to 20th	Night	18% 10% 33% 28% 10% 1	623
	21st to end	Night	17% 8% 29% 33% 13% 1	630
May	1st to 10th	Night	16% 9% 27% 29% 17% 2	603
	11th to 20th	Night	16% 5% 22% 33% 19% 4	591
	21st to end	Night	11% 3 15% 38% 28% 5%	650
June	1st to 10th	Night	9% 5% 15% 36% 30% 5%	600
	11th to 20th	Night	6% 2 12% 35% 37% 9%	600
	21st to end	Night	7% 2 13% 32% 37% 10%	600
July	1st to 10th	Night	11% 1 9% 27% 43% 10%	585
	11th to 20th	Night	10% 2 8% 26% 41% 13%	582
	21st to end	Night	11% 2 7% 29% 40% 12%	657
August	1st to 10th	Night	7% 2 7% 28% 47% 9%	597
	11th to 20th	Night	9% 2 10% 35% 39% 6%	594
	21st to end	Night	11% 2 8% 28% 41% 10%	660
September	1st to 10th	Night	12% 3 13% 27% 37% 7%	664
	11th to 20th	Night	11% 3 17% 30% 34% 6%	800
	21st to end	Night	12% 3 16% 31% 33% 4	800
October	1st to 10th	Night	13% 5% 20% 30% 26% 7%	800
	11th to 20th	Night	16% 9% 23% 33% 18% 1	800
	21st to end	Night	19% 9% 26% 31% 14% 2	880
November	1st to 10th	Night	17% 9% 23% 32% 16% 3	820
	11th to 20th	Night	17% 15% 30% 26% 11% 1	840
	21st to end	Night	22% 14% 25% 28% 9% 1	840
December	1st to 10th	Night	27% 16% 26% 26% 5%	840
	11th to 20th	Night	24% 15% 28% 26% 6% 1	840
	21st to end	Night	25% 19% 28% 24% 4	924

Page generated at 2026-04-29 01:21:43. Version ac07

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