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 2024-01-17.

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 6% 6% 3 5% 5% 6% 7% 37%	74881
	Night	13% 8% 3 6% 5% 3 4 5% 5% 7% 41%	74960
Transparency	Day	43% 8% 11% 19% 15% 3	74604
	Night	41% 7% 11% 20% 17% 4	74756
Seeing	Day	18% 12% 23% 22% 17% 9%	13507
	Night	17% 10% 23% 28% 19% 4	23601

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% 9% 4 7% 6% 3 5% 4 4 6% 33%	1706
	11th to 20th	Day	23% 12% 4 7% 5% 3 4 3 4 5% 31%	1674
	21st to end	Day	16% 9% 4 7% 4 2 4 4 4 6% 41%	1913
February	1st to 10th	Day	20% 12% 5% 7% 5% 3 3 3 4 5% 33%	1800
	11th to 20th	Day	22% 10% 4 7% 6% 3 4 4 5% 4 32%	1748
	21st to end	Day	22% 9% 4 7% 5% 3 3 4 3 6% 33%	1480
March	1st to 10th	Day	15% 11% 3 5% 5% 3 5% 4 6% 6% 38%	1800
	11th to 20th	Day	20% 9% 3 7% 5% 3 4 4 5% 6% 33%	1938
	21st to end	Day	16% 10% 4 6% 5% 4 5% 5% 5% 7% 32%	2215
April	1st to 10th	Day	13% 7% 2 5% 5% 3 5% 5% 6% 7% 43%	2160
	11th to 20th	Day	14% 8% 3 5% 5% 3 4 4 5% 6% 43%	2134
	21st to end	Day	15% 8% 3 6% 5% 3 4 4 5% 8% 39%	2235
May	1st to 10th	Day	15% 6% 2 5% 5% 3 4 6% 6% 8% 40%	2340
	11th to 20th	Day	15% 6% 3 7% 7% 4 6% 5% 5% 7% 35%	2301
	21st to end	Day	9% 6% 2 5% 6% 4 7% 6% 6% 9% 38%	2531
June	1st to 10th	Day	10% 5% 3 6% 6% 4 7% 6% 7% 9% 37%	2340
	11th to 20th	Day	6% 4 2 4 6% 4 7% 6% 7% 11% 42%	2340
	21st to end	Day	7% 5% 3 6% 7% 4 7% 6% 7% 11% 37%	2340
July	1st to 10th	Day	9% 7% 3 7% 8% 5% 8% 7% 7% 9% 29%	2340
	11th to 20th	Day	11% 5% 3 6% 7% 4 8% 8% 7% 9% 31%	2340
	21st to end	Day	9% 6% 3 7% 8% 5% 7% 7% 8% 10% 29%	2547
August	1st to 10th	Day	9% 6% 3 6% 8% 4 7% 7% 8% 11% 30%	2270
	11th to 20th	Day	10% 6% 3 6% 8% 4 7% 7% 6% 9% 33%	2125
	21st to end	Day	12% 6% 3 6% 7% 4 7% 8% 8% 9% 30%	2376
September	1st to 10th	Day	14% 6% 2 5% 6% 3 6% 6% 5% 8% 38%	2084
	11th to 20th	Day	12% 6% 3 6% 6% 4 5% 5% 6% 7% 39%	1980
	21st to end	Day	12% 4 2 5% 5% 3 5% 5% 5% 7% 46%	1980
October	1st to 10th	Day	11% 5% 2 4 4 3 4 4 4 5% 54%	1980
	11th to 20th	Day	13% 5% 2 4 4 3 3 3 5% 7% 51%	1954
	21st to end	Day	15% 7% 2 4 4 2 4 4 5% 6% 47%	1831
November	1st to 10th	Day	11% 5% 2 4 4 2 4 4 5% 4 56%	1672
	11th to 20th	Day	13% 7% 3 6% 4 2 4 4 4 6% 47%	1710
	21st to end	Day	16% 8% 2 5% 4 2 4 5% 5% 7% 42%	1710
December	1st to 10th	Day	19% 12% 4 6% 5% 3 4 4 5% 5% 33%	1710
	11th to 20th	Day	15% 12% 3 7% 6% 3 4 4 4 5% 35%	2153
	21st to end	Day	15% 13% 7% 7% 5% 2 4 5% 6% 7% 28%	3124
January	1st to 10th	Night	19% 9% 4 7% 6% 2 4 3 4 5% 37%	2459
	11th to 20th	Night	20% 13% 6% 7% 6% 2 4 3 5% 5% 29%	2430
	21st to end	Night	16% 11% 4 7% 5% 3 4 4 4 5% 38%	2439
February	1st to 10th	Night	18% 11% 4 7% 5% 2 4 3 5% 6% 34%	2160
	11th to 20th	Night	22% 10% 4 7% 5% 3 4 3 3 3 34%	2098
	21st to end	Night	23% 11% 4 7% 4 3 4 4 5% 6% 31%	1776
March	1st to 10th	Night	16% 9% 3 5% 5% 3 4 4 5% 7% 38%	2160
	11th to 20th	Night	17% 11% 4 6% 5% 3 4 5% 5% 6% 35%	2021
	21st to end	Night	15% 10% 3 6% 5% 3 5% 4 5% 6% 39%	2156
April	1st to 10th	Night	12% 6% 2 5% 4 3 4 4 6% 9% 46%	1800
	11th to 20th	Night	15% 6% 2 3 3 2 3 4 5% 7% 48%	1775
	21st to end	Night	14% 5% 2 4 6% 3 4 6% 6% 6% 44%	1724
May	1st to 10th	Night	12% 6% 2 5% 6% 2 4 5% 5% 7% 47%	1620
	11th to 20th	Night	12% 6% 2 5% 5% 3 5% 5% 6% 8% 43%	1592
	21st to end	Night	7% 6% 2 5% 5% 3 7% 6% 6% 10% 43%	1744
June	1st to 10th	Night	6% 7% 4 5% 5% 3 6% 6% 7% 10% 42%	1620
	11th to 20th	Night	4 3 1 4 3 3 5% 5% 8% 11% 54%	1620
	21st to end	Night	5% 4 3 6% 5% 4 6% 5% 6% 12% 45%	1620
July	1st to 10th	Night	9% 5% 3 5% 7% 4 5% 7% 7% 12% 36%	1620
	11th to 20th	Night	8% 4 2 5% 5% 3 6% 6% 6% 12% 44%	1620
	21st to end	Night	8% 6% 3 6% 5% 4 7% 7% 8% 12% 36%	1771
August	1st to 10th	Night	6% 4 1 5% 5% 4 6% 7% 8% 12% 42%	1664
	11th to 20th	Night	7% 6% 3 6% 6% 3 5% 6% 7% 10% 40%	1776
	21st to end	Night	9% 5% 2 5% 5% 3 6% 7% 7% 11% 40%	1980
September	1st to 10th	Night	10% 6% 2 5% 4 3 4 5% 7% 8% 46%	1857
	11th to 20th	Night	11% 5% 2 5% 5% 4 5% 5% 5% 7% 46%	1980
	21st to end	Night	7% 5% 2 5% 4 2 4 4 5% 8% 53%	1980
October	1st to 10th	Night	11% 5% 2 4 3 2 3 3 4 6% 58%	1980
	11th to 20th	Night	15% 5% 2 5% 4 2 4 4 5% 5% 49%	2006
	21st to end	Night	15% 7% 2 4 4 2 4 3 5% 5% 49%	2522
November	1st to 10th	Night	12% 6% 2 4 4 2 4 3 4 6% 52%	2406
	11th to 20th	Night	12% 8% 2 5% 4 3 3 4 5% 8% 47%	2470
	21st to end	Night	15% 9% 4 5% 4 2 4 4 5% 5% 42%	2470
December	1st to 10th	Night	19% 12% 4 6% 5% 3 5% 4 4 5% 33%	2470
	11th to 20th	Night	16% 10% 4 6% 5% 2 3 4 4 5% 40%	3042
	21st to end	Night	15% 15% 5% 8% 6% 3 5% 5% 5% 6% 27%	4532

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	51% 6% 7% 17% 16% 3	1707
	11th to 20th	Day	57% 3 7% 16% 14% 3	1674
	21st to end	Day	45% 4 10% 21% 18% 2	1913
February	1st to 10th	Day	55% 3 8% 16% 16% 3	1800
	11th to 20th	Day	55% 4 7% 17% 14% 3	1758
	21st to end	Day	53% 5% 7% 13% 16% 6%	1480
March	1st to 10th	Day	46% 6% 8% 16% 19% 7%	1800
	11th to 20th	Day	51% 7% 10% 15% 14% 3	1938
	21st to end	Day	50% 7% 11% 19% 12% 1	2215
April	1st to 10th	Day	38% 8% 11% 23% 17% 3	2160
	11th to 20th	Day	41% 6% 8% 17% 24% 4	2134
	21st to end	Day	43% 6% 9% 25% 15% 2	2235
May	1st to 10th	Day	39% 9% 12% 24% 13% 3	2340
	11th to 20th	Day	46% 10% 12% 19% 12%	2305
	21st to end	Day	40% 11% 13% 21% 13% 1	2531
June	1st to 10th	Day	40% 11% 14% 21% 13% 1	2340
	11th to 20th	Day	32% 12% 17% 22% 14% 2	2340
	21st to end	Day	37% 12% 18% 17% 12% 3	2340
July	1st to 10th	Day	45% 12% 15% 18% 9% 2	2275
	11th to 20th	Day	44% 13% 17% 14% 9% 3	2271
	21st to end	Day	42% 14% 16% 19% 8% 1	2405
August	1st to 10th	Day	42% 14% 19% 16% 8% 1	2257
	11th to 20th	Day	45% 11% 15% 17% 11% 1	2125
	21st to end	Day	44% 14% 13% 16% 10% 2	2376
September	1st to 10th	Day	41% 11% 13% 16% 14% 4	2084
	11th to 20th	Day	42% 9% 11% 19% 18% 2	1980
	21st to end	Day	36% 7% 12% 21% 19% 6%	1980
October	1st to 10th	Day	32% 6% 9% 22% 26% 6%	1980
	11th to 20th	Day	32% 6% 9% 21% 23% 9%	1954
	21st to end	Day	37% 6% 7% 20% 24% 6%	1831
November	1st to 10th	Day	31% 5% 8% 20% 29% 7%	1672
	11th to 20th	Day	39% 4 6% 22% 22% 7%	1710
	21st to end	Day	42% 4 8% 20% 21% 5%	1710
December	1st to 10th	Day	54% 5% 6% 19% 13% 3	1710
	11th to 20th	Day	50% 7% 8% 15% 18% 3	2150
	21st to end	Day	51% 6% 11% 18% 12% 2	3124
January	1st to 10th	Night	50% 5% 8% 18% 16% 4	2459
	11th to 20th	Night	57% 4 7% 14% 13% 3	2430
	21st to end	Night	48% 5% 7% 20% 16% 3	2439
February	1st to 10th	Night	52% 4 10% 16% 16% 3	2160
	11th to 20th	Night	56% 4 5% 16% 14% 5%	2099
	21st to end	Night	55% 5% 7% 15% 12% 5%	1776
March	1st to 10th	Night	45% 6% 9% 14% 19% 8%	2160
	11th to 20th	Night	48% 8% 8% 19% 15% 2	2021
	21st to end	Night	46% 5% 11% 23% 13% 2	2156
April	1st to 10th	Night	35% 7% 12% 22% 21% 3	1800
	11th to 20th	Night	35% 5% 9% 20% 23% 7%	1775
	21st to end	Night	38% 7% 11% 26% 16% 2	1724
May	1st to 10th	Night	36% 6% 12% 24% 20% 2	1620
	11th to 20th	Night	39% 10% 17% 21% 13% 1	1593
	21st to end	Night	33% 12% 15% 23% 13% 2	1745
June	1st to 10th	Night	35% 10% 15% 24% 13% 2	1620
	11th to 20th	Night	22% 10% 20% 33% 14% 2	1620
	21st to end	Night	31% 10% 17% 24% 14% 4	1620
July	1st to 10th	Night	37% 14% 18% 18% 12% 2	1575
	11th to 20th	Night	30% 11% 20% 22% 12% 4	1566
	21st to end	Night	34% 12% 19% 23% 10% 2	1672
August	1st to 10th	Night	31% 12% 20% 26% 11%	1653
	11th to 20th	Night	35% 12% 20% 17% 14% 2	1776
	21st to end	Night	35% 12% 17% 22% 12% 2	1980
September	1st to 10th	Night	33% 9% 17% 20% 16% 5%	1857
	11th to 20th	Night	36% 9% 11% 20% 22% 2	1980
	21st to end	Night	30% 7% 10% 24% 22% 6%	1980
October	1st to 10th	Night	28% 4 9% 25% 25% 9%	1980
	11th to 20th	Night	35% 6% 9% 21% 21% 8%	2006
	21st to end	Night	37% 4 6% 21% 25% 8%	2522
November	1st to 10th	Night	34% 5% 7% 21% 25% 8%	2406
	11th to 20th	Night	35% 5% 8% 19% 25% 8%	2470
	21st to end	Night	43% 4 6% 19% 21% 5%	2470
December	1st to 10th	Night	54% 5% 8% 16% 15% 3	2470
	11th to 20th	Night	44% 7% 7% 16% 22% 4	3044
	21st to end	Night	53% 7% 10% 17% 11% 2	4532

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	24% 27% 32% 13% 3	270
	11th to 20th	Day	33% 28% 24% 12% 2 1	258
	21st to end	Day	24% 29% 35% 9% 3	264
February	1st to 10th	Day	32% 26% 29% 12% 1	240
	11th to 20th	Day	41% 25% 26% 7%	240
	21st to end	Day	36% 26% 30% 7% 1	198
March	1st to 10th	Day	26% 22% 39% 10% 3	240
	11th to 20th	Day	25% 25% 28% 16% 5% 1	378
	21st to end	Day	27% 18% 32% 14% 8%	462
April	1st to 10th	Day	19% 21% 28% 22% 11%	420
	11th to 20th	Day	20% 17% 31% 20% 11% 1	412
	21st to end	Day	22% 15% 28% 20% 12% 2	420
May	1st to 10th	Day	17% 14% 30% 23% 11% 5%	423
	11th to 20th	Day	14% 9% 27% 23% 17% 9%	447
	21st to end	Day	13% 5% 20% 31% 16% 15%	485
June	1st to 10th	Day	12% 4 22% 25% 22% 15%	450
	11th to 20th	Day	7% 4 14% 28% 28% 20%	450
	21st to end	Day	10% 4 20% 27% 23% 16%	450
July	1st to 10th	Day	11% 3 13% 27% 24% 22%	445
	11th to 20th	Day	9% 6% 11% 21% 29% 25%	444
	21st to end	Day	10% 2 10% 26% 30% 22%	488
August	1st to 10th	Day	13% 4 11% 26% 27% 18%	446
	11th to 20th	Day	11% 4 12% 31% 31% 11%	439
	21st to end	Day	15% 3 9% 23% 34% 17%	495
September	1st to 10th	Day	13% 4 10% 25% 32% 16%	450
	11th to 20th	Day	13% 6% 14% 24% 28% 15%	450
	21st to end	Day	15% 5% 16% 28% 28% 7%	450
October	1st to 10th	Day	14% 5% 22% 30% 21% 8%	450
	11th to 20th	Day	14% 13% 31% 24% 14% 3	450
	21st to end	Day	21% 10% 28% 27% 11% 2	346
November	1st to 10th	Day	17% 11% 32% 28% 10% 2	270
	11th to 20th	Day	14% 20% 41% 22% 3	270
	21st to end	Day	20% 20% 34% 14% 10% 1	270
December	1st to 10th	Day	31% 18% 30% 17% 4	270
	11th to 20th	Day	24% 22% 30% 16% 7%	270
	21st to end	Day	26% 24% 34% 13% 3	297
January	1st to 10th	Night	25% 19% 34% 19% 4	760
	11th to 20th	Night	28% 21% 28% 19% 4	748
	21st to end	Night	21% 19% 35% 22% 3	792
February	1st to 10th	Night	24% 17% 33% 23% 4	720
	11th to 20th	Night	30% 18% 33% 17% 2	703
	21st to end	Night	31% 18% 31% 18% 2	592
March	1st to 10th	Night	20% 17% 33% 26% 4	720
	11th to 20th	Night	22% 16% 31% 24% 7% 1	720
	21st to end	Night	22% 14% 29% 25% 10% 1	770
April	1st to 10th	Night	15% 15% 27% 31% 12%	540
	11th to 20th	Night	20% 9% 32% 28% 11% 2	533
	21st to end	Night	16% 7% 28% 34% 13% 1	540
May	1st to 10th	Night	15% 8% 28% 29% 18% 2	540
	11th to 20th	Night	16% 4 22% 33% 21% 5%	531
	21st to end	Night	10% 3 13% 38% 31% 6%	584
June	1st to 10th	Night	8% 4 14% 36% 33% 5%	540
	11th to 20th	Night	5% 1 11% 35% 39% 10%	540
	21st to end	Night	7% 1 14% 33% 36% 9%	540
July	1st to 10th	Night	11% 1 9% 26% 43% 10%	525
	11th to 20th	Night	10% 2 8% 26% 40% 13%	522
	21st to end	Night	9% 2 6% 30% 42% 12%	591
August	1st to 10th	Night	7% 1 6% 26% 50% 10%	537
	11th to 20th	Night	9% 2 8% 35% 40% 7%	534
	21st to end	Night	12% 1 7% 28% 42% 10%	594
September	1st to 10th	Night	13% 3 10% 27% 39% 8%	597
	11th to 20th	Night	11% 2 17% 29% 33% 7%	720
	21st to end	Night	10% 2 16% 32% 35% 4	720
October	1st to 10th	Night	13% 5% 19% 30% 26% 7%	720
	11th to 20th	Night	17% 9% 23% 31% 18% 2	720
	21st to end	Night	19% 9% 25% 30% 14% 2	792
November	1st to 10th	Night	16% 9% 21% 33% 18% 3	740
	11th to 20th	Night	16% 15% 30% 26% 12% 1	760
	21st to end	Night	21% 13% 25% 30% 9% 1	760
December	1st to 10th	Night	26% 16% 26% 27% 5%	760
	11th to 20th	Night	23% 15% 27% 28% 7% 1	760
	21st to end	Night	25% 18% 29% 24% 4	836

Page generated at 2024-01-14 08:55:00. Version ac07

Copyright 2024 Attilla Danko