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 2025-01-07.

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%	104966
	Night	14% 9% 3 6% 4 4 4 3 5% 7% 41%	104040
Transparency	Day	42% 8% 11% 20% 16% 4	108733
	Night	40% 7% 10% 20% 18% 5%	108411
Seeing	Day	18% 12% 24% 22% 16% 8%	14799
	Night	17% 10% 23% 28% 18% 3	24861

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	16% 13% 6% 9% 6% 4 5% 4 4 5% 28%	2890
	11th to 20th	Day	20% 11% 4 12% 4 3 4 3 3 4 32%	2840
	21st to end	Day	22% 11% 6% 7% 3 3 4 3 4 5% 31%	3353
February	1st to 10th	Day	20% 12% 4 8% 4 3 3 3 4 5% 34%	1900
	11th to 20th	Day	21% 11% 4 8% 5% 4 3 3 4 4 33%	1848
	21st to end	Day	21% 9% 4 8% 5% 4 3 3 4 5% 33%	1570
March	1st to 10th	Day	21% 11% 3 7% 5% 3 4 4 6% 6% 30%	3120
	11th to 20th	Day	15% 8% 2 6% 4 4 3 3 4 6% 45%	3410
	21st to end	Day	14% 9% 3 7% 5% 5% 4 4 5% 7% 36%	3892
April	1st to 10th	Day	13% 7% 2 5% 5% 4 5% 4 6% 7% 41%	2280
	11th to 20th	Day	14% 8% 3 6% 4 4 3 3 5% 6% 42%	2254
	21st to end	Day	14% 9% 2 7% 4 4 4 3 5% 8% 40%	2360
May	1st to 10th	Day	17% 8% 2 6% 5% 4 5% 5% 7% 8% 35%	4082
	11th to 20th	Day	16% 9% 3 8% 5% 5% 5% 4 5% 8% 32%	4081
	21st to end	Day	12% 7% 3 6% 5% 5% 5% 5% 6% 8% 39%	4476
June	1st to 10th	Day	10% 6% 3 7% 5% 5% 6% 5% 7% 9% 36%	2470
	11th to 20th	Day	6% 4 2 5% 5% 6% 7% 5% 7% 11% 42%	2470
	21st to end	Day	6% 5% 2 6% 7% 6% 6% 5% 8% 11% 37%	2470
July	1st to 10th	Day	7% 6% 2 7% 7% 7% 8% 6% 7% 11% 33%	4120
	11th to 20th	Day	11% 6% 2 7% 6% 6% 7% 5% 7% 9% 32%	4120
	21st to end	Day	18% 11% 4 10% 8% 6% 6% 5% 6% 7% 19%	4466
August	1st to 10th	Day	6% 5% 2 5% 5% 5% 6% 5% 9% 11% 43%	3991
	11th to 20th	Day	7% 5% 2 7% 6% 6% 7% 6% 7% 10% 37%	3729
	21st to end	Day	7% 4 2 6% 5% 6% 7% 5% 7% 9% 42%	4180
September	1st to 10th	Day	13% 6% 2 6% 5% 5% 7% 5% 5% 8% 38%	2199
	11th to 20th	Day	12% 6% 3 7% 5% 5% 5% 4 7% 7% 39%	2090
	21st to end	Day	13% 5% 2 6% 5% 4 5% 4 6% 6% 44%	2090
October	1st to 10th	Day	10% 5% 2 4 4 4 4 3 4 5% 55%	2090
	11th to 20th	Day	13% 5% 2 4 3 4 3 2 5% 7% 53%	2062
	21st to end	Day	14% 7% 2 5% 3 4 3 3 5% 6% 48%	1932
November	1st to 10th	Day	11% 6% 2 5% 4 3 4 3 5% 4 53%	1762
	11th to 20th	Day	13% 8% 3 6% 4 3 4 3 4 6% 46%	1800
	21st to end	Day	15% 10% 2 6% 4 3 4 3 5% 6% 42%	1800
December	1st to 10th	Day	16% 10% 3 6% 5% 4 4 3 4 4 42%	2930
	11th to 20th	Day	16% 15% 6% 11% 5% 4 4 3 4 4 29%	3373
	21st to end	Day	16% 13% 6% 8% 4 3 4 3 6% 8% 28%	4466
January	1st to 10th	Night	18% 15% 4 7% 4 3 3 3 4 5% 35%	4188
	11th to 20th	Night	19% 13% 5% 7% 6% 4 3 2 4 4 34%	4120
	21st to end	Night	22% 15% 5% 6% 4 3 3 2 3 4 34%	4299
February	1st to 10th	Night	17% 12% 3 8% 4 3 4 3 5% 5% 35%	2280
	11th to 20th	Night	21% 11% 4 8% 5% 4 4 3 3 3 34%	2218
	21st to end	Night	22% 12% 3 8% 3 4 3 3 5% 5% 31%	1884
March	1st to 10th	Night	21% 14% 3 7% 4 4 4 3 5% 6% 29%	3733
	11th to 20th	Night	13% 9% 2 5% 4 4 4 4 5% 6% 46%	3549
	21st to end	Night	14% 9% 3 8% 6% 5% 4 3 4 5% 38%	3768
April	1st to 10th	Night	13% 7% 2 5% 4 4 3 4 6% 8% 45%	1900
	11th to 20th	Night	15% 7% 2 4 3 4 3 3 5% 7% 47%	1875
	21st to end	Night	14% 6% 2 5% 5% 4 4 5% 6% 6% 44%	1819
May	1st to 10th	Night	13% 7% 2 6% 5% 4 5% 4 6% 7% 40%	2813
	11th to 20th	Night	15% 9% 3 7% 5% 4 4 3 5% 7% 37%	2812
	21st to end	Night	7% 6% 2 6% 4 5% 6% 5% 7% 10% 41%	3079
June	1st to 10th	Night	6% 8% 3 6% 4 5% 5% 5% 7% 10% 40%	1710
	11th to 20th	Night	4 3 1 4 3 4 4 4 8% 10% 54%	1710
	21st to end	Night	5% 5% 2 7% 4 6% 4 5% 7% 11% 45%	1710
July	1st to 10th	Night	9% 6% 2 6% 5% 5% 6% 5% 8% 11% 37%	2840
	11th to 20th	Night	9% 5% 2 6% 4 4 5% 4 6% 11% 42%	2840
	21st to end	Night	14% 10% 4 10% 6% 6% 6% 5% 7% 8% 24%	3087
August	1st to 10th	Night	4 4 1 5% 4 4 4 4 7% 11% 52%	2920
	11th to 20th	Night	6% 5% 2 6% 4 4 4 4 7% 10% 46%	3100
	21st to end	Night	5% 4 2 4 4 4 5% 4 6% 9% 54%	3476
September	1st to 10th	Night	10% 7% 2 6% 3 4 4 4 7% 8% 46%	1961
	11th to 20th	Night	10% 5% 2 6% 5% 5% 5% 4 5% 7% 45%	2090
	21st to end	Night	9% 6% 2 5% 4 4 4 3 5% 8% 51%	2090
October	1st to 10th	Night	10% 5% 2 4 3 2 3 3 4 6% 59%	2090
	11th to 20th	Night	14% 5% 2 5% 3 3 3 3 5% 5% 51%	2118
	21st to end	Night	14% 7% 2 5% 3 3 3 2 5% 5% 50%	2663
November	1st to 10th	Night	12% 7% 2 5% 4 3 3 3 5% 6% 50%	2536
	11th to 20th	Night	12% 9% 2 5% 4 3 2 4 5% 7% 47%	2600
	21st to end	Night	15% 10% 4 6% 3 3 4 3 5% 5% 42%	2600
December	1st to 10th	Night	18% 12% 3 7% 4 3 4 3 4 4 39%	4250
	11th to 20th	Night	20% 13% 4 7% 4 3 3 2 4 4 36%	4822
	21st to end	Night	14% 15% 6% 9% 5% 4 4 3 5% 6% 30%	6490

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	52% 8% 8% 15% 15% 2	2891
	11th to 20th	Day	55% 5% 6% 12% 19% 2	2840
	21st to end	Day	54% 4 8% 19% 14% 1	3353
February	1st to 10th	Day	54% 4 7% 16% 17% 3	1900
	11th to 20th	Day	54% 4 7% 16% 15% 4	1858
	21st to end	Day	52% 5% 7% 14% 16% 5%	1570
March	1st to 10th	Day	52% 9% 8% 12% 12% 8%	3120
	11th to 20th	Day	40% 6% 8% 22% 18% 6%	3410
	21st to end	Day	45% 7% 11% 22% 14% 1	3892
April	1st to 10th	Day	39% 8% 11% 22% 17% 3	2280
	11th to 20th	Day	41% 6% 7% 17% 24% 4	2254
	21st to end	Day	42% 7% 10% 25% 15% 2	2360
May	1st to 10th	Day	42% 11% 12% 22% 11% 2	4120
	11th to 20th	Day	47% 10% 13% 22% 8%	4085
	21st to end	Day	39% 10% 11% 21% 17% 1	4489
June	1st to 10th	Day	41% 11% 14% 21% 13% 1	2470
	11th to 20th	Day	32% 12% 17% 22% 15% 2	2470
	21st to end	Day	37% 12% 18% 17% 13% 3	2470
July	1st to 10th	Day	40% 12% 20% 21% 6% 1	4055
	11th to 20th	Day	43% 11% 18% 21% 6% 1	4051
	21st to end	Day	60% 10% 11% 13% 5%	4324
August	1st to 10th	Day	31% 10% 16% 30% 12% 1	3978
	11th to 20th	Day	38% 8% 16% 24% 13% 1	3765
	21st to end	Day	33% 11% 13% 26% 15% 1	4179
September	1st to 10th	Day	41% 11% 13% 16% 15% 5%	2199
	11th to 20th	Day	42% 9% 11% 19% 18% 2	2090
	21st to end	Day	38% 7% 12% 20% 18% 5%	2090
October	1st to 10th	Day	25% 4 7% 16% 35% 13%	3480
	11th to 20th	Day	23% 4 6% 22% 29% 17%	3406
	21st to end	Day	28% 5% 8% 24% 26% 11%	3156
November	1st to 10th	Day	33% 5% 9% 20% 27% 6%	1762
	11th to 20th	Day	39% 4 6% 22% 22% 7%	1800
	21st to end	Day	42% 4 8% 21% 21% 4	1800
December	1st to 10th	Day	45% 4 5% 21% 22% 3	2930
	11th to 20th	Day	58% 5% 6% 16% 13% 3	3370
	21st to end	Day	52% 6% 11% 20% 11% 2	4466
January	1st to 10th	Night	49% 6% 7% 17% 18% 2	4188
	11th to 20th	Night	53% 5% 6% 13% 17% 7%	4120
	21st to end	Night	55% 4 6% 14% 18% 3	4299
February	1st to 10th	Night	51% 4 10% 16% 17% 3	2280
	11th to 20th	Night	55% 5% 5% 16% 14% 5%	2219
	21st to end	Night	54% 5% 7% 15% 13% 5%	1884
March	1st to 10th	Night	55% 8% 8% 9% 14% 5%	3733
	11th to 20th	Night	37% 7% 7% 22% 16% 10%	3549
	21st to end	Night	47% 6% 9% 20% 16% 2	3768
April	1st to 10th	Night	36% 7% 12% 21% 20% 3	1900
	11th to 20th	Night	35% 5% 9% 20% 23% 7%	1875
	21st to end	Night	38% 7% 11% 26% 16% 2	1819
May	1st to 10th	Night	39% 10% 14% 23% 13% 1	2840
	11th to 20th	Night	45% 9% 14% 19% 12%	2813
	21st to end	Night	31% 14% 16% 24% 14% 1	3087
June	1st to 10th	Night	36% 10% 15% 23% 13% 2	1710
	11th to 20th	Night	22% 9% 19% 33% 15% 2	1710
	21st to end	Night	31% 9% 17% 24% 14% 4	1710
July	1st to 10th	Night	37% 12% 20% 22% 8% 1	2795
	11th to 20th	Night	33% 9% 22% 27% 7% 2	2786
	21st to end	Night	55% 10% 13% 15% 6% 1	2988
August	1st to 10th	Night	24% 8% 14% 36% 17% 1	2909
	11th to 20th	Night	30% 8% 23% 24% 14% 1	3130
	21st to end	Night	25% 9% 14% 30% 21% 1	3476
September	1st to 10th	Night	34% 9% 17% 19% 16% 6%	1961
	11th to 20th	Night	37% 9% 11% 20% 22% 2	2090
	21st to end	Night	31% 7% 11% 23% 21% 6%	2090
October	1st to 10th	Night	22% 3 7% 22% 29% 17%	3480
	11th to 20th	Night	22% 4 5% 20% 29% 19%	3513
	21st to end	Night	24% 3 6% 26% 29% 11%	4389
November	1st to 10th	Night	35% 5% 8% 20% 24% 8%	2536
	11th to 20th	Night	36% 5% 8% 19% 25% 8%	2600
	21st to end	Night	43% 4 6% 20% 21% 5%	2600
December	1st to 10th	Night	49% 3 6% 14% 25% 3	4250
	11th to 20th	Night	51% 5% 5% 17% 20% 3	4824
	21st to end	Night	53% 6% 10% 20% 10% 1	6490

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	25% 27% 32% 13% 3	288
	11th to 20th	Day	34% 27% 24% 12% 2 1	270
	21st to end	Day	25% 28% 35% 9% 2	297
February	1st to 10th	Day	31% 25% 30% 12% 2	270
	11th to 20th	Day	39% 25% 27% 7% 1 1	270
	21st to end	Day	40% 25% 28% 6%	225
March	1st to 10th	Day	29% 20% 36% 12% 3	270
	11th to 20th	Day	25% 25% 29% 17% 4 1	416
	21st to end	Day	27% 19% 33% 13% 7%	506
April	1st to 10th	Day	20% 22% 27% 20% 10%	460
	11th to 20th	Day	21% 18% 30% 19% 10% 1	452
	21st to end	Day	21% 16% 30% 20% 11% 2	460
May	1st to 10th	Day	16% 15% 31% 21% 11% 5%	463
	11th to 20th	Day	15% 9% 27% 23% 17% 8%	487
	21st to end	Day	12% 6% 22% 31% 15% 14%	529
June	1st to 10th	Day	12% 6% 23% 24% 21% 14%	490
	11th to 20th	Day	6% 4 15% 29% 27% 18%	490
	21st to end	Day	10% 4 21% 28% 22% 16%	490
July	1st to 10th	Day	11% 3 14% 29% 24% 20%	485
	11th to 20th	Day	10% 6% 11% 23% 27% 23%	484
	21st to end	Day	12% 2 11% 26% 28% 20%	532
August	1st to 10th	Day	13% 4 13% 26% 27% 18%	486
	11th to 20th	Day	10% 5% 16% 30% 29% 10%	479
	21st to end	Day	14% 3 8% 23% 35% 17%	539
September	1st to 10th	Day	12% 5% 12% 26% 30% 15%	490
	11th to 20th	Day	13% 6% 16% 24% 27% 14%	490
	21st to end	Day	17% 5% 17% 27% 27% 7%	490
October	1st to 10th	Day	13% 5% 22% 31% 20% 8%	490
	11th to 20th	Day	13% 12% 31% 26% 14% 3	490
	21st to end	Day	19% 10% 30% 27% 12% 2	381
November	1st to 10th	Day	17% 12% 33% 25% 10% 2	300
	11th to 20th	Day	15% 20% 40% 21% 4	300
	21st to end	Day	21% 20% 33% 15% 9% 1	300
December	1st to 10th	Day	31% 19% 31% 15% 4	300
	11th to 20th	Day	26% 21% 30% 15% 7%	300
	21st to end	Day	26% 23% 34% 13% 4	330
January	1st to 10th	Night	25% 19% 34% 19% 3	785
	11th to 20th	Night	29% 21% 28% 18% 4	760
	21st to end	Night	21% 19% 35% 22% 2	836
February	1st to 10th	Night	23% 17% 32% 24% 4	760
	11th to 20th	Night	30% 18% 31% 19% 2	743
	21st to end	Night	30% 19% 32% 17% 2	628
March	1st to 10th	Night	21% 17% 32% 25% 4	760
	11th to 20th	Night	22% 16% 31% 24% 7% 1	760
	21st to end	Night	22% 15% 29% 25% 10%	812
April	1st to 10th	Night	15% 16% 27% 30% 11%	570
	11th to 20th	Night	20% 10% 31% 28% 10% 1	563
	21st to end	Night	16% 8% 29% 33% 13% 1	570
May	1st to 10th	Night	15% 8% 27% 29% 18% 2	570
	11th to 20th	Night	16% 4 22% 33% 20% 4	561
	21st to end	Night	9% 3 14% 39% 30% 6%	617
June	1st to 10th	Night	9% 5% 14% 36% 31% 5%	570
	11th to 20th	Night	5% 1 11% 35% 38% 10%	570
	21st to end	Night	7% 2 14% 33% 36% 9%	570
July	1st to 10th	Night	11% 1 9% 27% 42% 10%	555
	11th to 20th	Night	10% 2 8% 27% 40% 13%	552
	21st to end	Night	11% 2 7% 29% 40% 11%	624
August	1st to 10th	Night	7% 1 6% 27% 49% 10%	567
	11th to 20th	Night	9% 2 10% 35% 38% 6%	564
	21st to end	Night	11% 1 7% 28% 42% 10%	627
September	1st to 10th	Night	13% 3 12% 27% 38% 8%	631
	11th to 20th	Night	11% 3 18% 29% 33% 7%	760
	21st to end	Night	12% 3 16% 32% 34% 4	760
October	1st to 10th	Night	13% 5% 19% 30% 26% 7%	760
	11th to 20th	Night	16% 9% 23% 31% 19% 1	760
	21st to end	Night	19% 8% 25% 31% 15% 2	836
November	1st to 10th	Night	17% 10% 22% 32% 17% 3	780
	11th to 20th	Night	17% 16% 30% 26% 11% 1	800
	21st to end	Night	22% 13% 26% 30% 9% 1	800
December	1st to 10th	Night	26% 17% 26% 26% 5%	800
	11th to 20th	Night	24% 15% 27% 27% 7% 1	800
	21st to end	Night	24% 19% 28% 24% 4	880

Page generated at 2025-01-04 02:24:00. Version ac07

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