Schroon Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Schroon Lake clear sky chart from 2005-11-06 to 2024-08-15.

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	16% 9% 3 8% 6% 5% 5% 4 6% 7% 32%	95588
	Night	16% 10% 3 8% 5% 5% 4 4 5% 6% 33%	93147
Transparency	Day	52% 4 11% 21% 11% 1	95307
	Night	52% 4 12% 21% 11% 1	92982
Seeing	Day	22% 16% 30% 20% 9% 3	14415
	Night	21% 13% 28% 28% 10% 1	23399

By Month

Percentage Cloud Cover NE (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	11% 14% 5% 11% 7% 6% 5% 4 5% 5% 26%	2517
	11th to 20th	Day	12% 15% 5% 17% 9% 5% 4 4 4 4 20%	2520
	21st to end	Day	13% 15% 6% 12% 7% 7% 5% 4 5% 6% 21%	2801
February	1st to 10th	Day	11% 12% 5% 10% 8% 7% 5% 4 7% 6% 25%	1710
	11th to 20th	Day	9% 12% 5% 10% 7% 6% 5% 4 7% 7% 28%	1796
	21st to end	Day	16% 12% 4 9% 6% 6% 5% 3 5% 6% 28%	1570
March	1st to 10th	Day	19% 17% 5% 11% 5% 5% 4 3 4 5% 23%	3116
	11th to 20th	Day	12% 14% 5% 10% 6% 6% 5% 5% 6% 6% 27%	3284
	21st to end	Day	16% 12% 3 8% 5% 4 4 3 4 5% 36%	4161
April	1st to 10th	Day	20% 12% 2 7% 5% 4 4 3 4 6% 33%	2280
	11th to 20th	Day	18% 10% 3 7% 5% 4 5% 3 5% 5% 35%	2254
	21st to end	Day	22% 9% 3 8% 5% 5% 5% 3 5% 5% 29%	2394
May	1st to 10th	Day	22% 11% 3 8% 5% 5% 4 3 4 6% 28%	4259
	11th to 20th	Day	17% 9% 3 8% 6% 5% 5% 4 5% 7% 30%	4398
	21st to end	Day	14% 5% 2 7% 5% 5% 5% 5% 6% 8% 38%	4837
June	1st to 10th	Day	18% 6% 3 8% 6% 6% 5% 5% 7% 8% 28%	2660
	11th to 20th	Day	16% 7% 3 6% 6% 6% 5% 5% 6% 8% 34%	2660
	21st to end	Day	19% 7% 3 7% 5% 5% 5% 5% 8% 7% 30%	2660
July	1st to 10th	Day	12% 5% 2 6% 6% 5% 6% 5% 7% 9% 37%	4440
	11th to 20th	Day	12% 6% 2 5% 5% 5% 6% 5% 7% 10% 38%	4440
	21st to end	Day	15% 5% 2 6% 5% 6% 6% 5% 7% 8% 36%	4814
August	1st to 10th	Day	13% 5% 2 7% 6% 6% 6% 5% 6% 8% 36%	2646
	11th to 20th	Day	13% 5% 2 7% 6% 6% 6% 4 8% 10% 33%	2239
	21st to end	Day	14% 6% 2 6% 5% 4 6% 5% 6% 8% 38%	2376
September	1st to 10th	Day	14% 5% 2 5% 5% 4 5% 4 6% 8% 41%	2160
	11th to 20th	Day	14% 6% 2 6% 3 4 4 3 5% 7% 45%	2080
	21st to end	Day	19% 5% 3 5% 4 4 4 4 6% 8% 39%	1980
October	1st to 10th	Day	24% 8% 3 7% 5% 4 3 4 5% 4 32%	1872
	11th to 20th	Day	17% 9% 3 7% 4 4 4 4 7% 6% 34%	1788
	21st to end	Day	23% 11% 3 8% 6% 4 4 3 5% 6% 27%	1782
November	1st to 10th	Day	13% 9% 3 8% 5% 6% 4 4 6% 7% 35%	1671
	11th to 20th	Day	15% 9% 3 8% 6% 6% 6% 4 5% 5% 32%	1705
	21st to end	Day	17% 10% 4 9% 5% 5% 5% 4 6% 6% 28%	1520
December	1st to 10th	Day	18% 16% 5% 9% 8% 4 5% 4 4 7% 20%	1520
	11th to 20th	Day	21% 13% 3 8% 5% 4 3 4 5% 7% 27%	1906
	21st to end	Day	21% 17% 5% 10% 6% 4 4 2 4 4 23%	2772
January	1st to 10th	Night	14% 12% 4 10% 7% 6% 4 4 6% 6% 28%	4429
	11th to 20th	Night	10% 13% 5% 18% 10% 6% 5% 4 5% 6% 19%	4440
	21st to end	Night	16% 14% 5% 11% 6% 4 4 4 5% 5% 25%	4852
February	1st to 10th	Night	11% 12% 5% 12% 7% 6% 5% 5% 6% 6% 25%	2470
	11th to 20th	Night	9% 11% 4 9% 8% 6% 6% 4 6% 7% 31%	2270
	21st to end	Night	14% 11% 4 10% 5% 4 5% 3 6% 7% 31%	1884
March	1st to 10th	Night	22% 13% 2 6% 5% 4 5% 4 5% 5% 27%	3724
	11th to 20th	Night	13% 12% 4 10% 6% 5% 5% 4 5% 5% 32%	3671
	21st to end	Night	15% 10% 3 10% 6% 4 4 3 4 4 36%	3471
April	1st to 10th	Night	18% 9% 3 7% 5% 4 4 4 5% 6% 34%	1900
	11th to 20th	Night	18% 10% 3 7% 5% 4 4 4 6% 7% 33%	1875
	21st to end	Night	20% 8% 3 7% 4 3 4 4 5% 5% 35%	1786
May	1st to 10th	Night	25% 10% 3 7% 5% 4 5% 4 6% 6% 26%	2710
	11th to 20th	Night	20% 11% 4 9% 5% 4 3 3 4 5% 31%	2495
	21st to end	Night	14% 6% 2 6% 5% 4 5% 4 7% 8% 38%	2738
June	1st to 10th	Night	18% 6% 2 6% 4 4 5% 4 5% 8% 38%	1520
	11th to 20th	Night	18% 6% 2 5% 4 4 4 4 5% 8% 40%	1520
	21st to end	Night	17% 6% 2 6% 4 5% 5% 4 6% 7% 37%	1520
July	1st to 10th	Night	12% 6% 2 7% 5% 6% 5% 5% 5% 7% 39%	2520
	11th to 20th	Night	14% 5% 1 5% 4 4 4 4 6% 8% 45%	2520
	21st to end	Night	12% 7% 2 5% 4 4 5% 4 6% 7% 43%	2739
August	1st to 10th	Night	11% 5% 1 5% 4 4 5% 5% 7% 7% 45%	1512
	11th to 20th	Night	13% 5% 2 6% 5% 4 5% 4 8% 8% 41%	1738
	21st to end	Night	13% 5% 1 5% 4 3 4 5% 5% 8% 47%	1980
September	1st to 10th	Night	12% 5% 2 5% 5% 4 3 4 6% 8% 45%	1800
	11th to 20th	Night	14% 6% 2 5% 2 4 4 3 4 6% 50%	1880
	21st to end	Night	17% 6% 1 6% 3 4 4 3 5% 6% 45%	1980
October	1st to 10th	Night	19% 8% 3 8% 5% 5% 4 3 4 6% 34%	2086
	11th to 20th	Night	16% 6% 3 7% 5% 6% 6% 3 6% 6% 35%	2170
	21st to end	Night	21% 10% 3 7% 5% 4 5% 4 5% 6% 29%	2574
November	1st to 10th	Night	13% 9% 3 7% 5% 5% 5% 4 6% 6% 37%	2407
	11th to 20th	Night	17% 8% 3 7% 5% 5% 5% 3 5% 7% 35%	2474
	21st to end	Night	15% 10% 3 8% 5% 5% 5% 4 6% 8% 31%	2660
December	1st to 10th	Night	17% 14% 4 11% 6% 5% 4 4 6% 7% 22%	2660
	11th to 20th	Night	19% 11% 3 9% 6% 4 5% 4 5% 6% 28%	3288
	21st to end	Night	21% 14% 5% 11% 5% 5% 4 4 4 6% 21%	4884

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	59% 2 9% 23% 6% 2	2518
	11th to 20th	Day	68% 3 7% 15% 5% 1	2520
	21st to end	Day	65% 2 12% 14% 7% 1	2801
February	1st to 10th	Day	58% 5% 11% 19% 6% 2	1710
	11th to 20th	Day	56% 4 10% 17% 12% 2	1805
	21st to end	Day	58% 3 10% 16% 11% 2	1570
March	1st to 10th	Day	65% 2 8% 13% 10% 2	3119
	11th to 20th	Day	58% 2 12% 16% 10% 2	3284
	21st to end	Day	53% 2 5% 16% 21% 3	4161
April	1st to 10th	Day	53% 3 9% 20% 12% 3	2280
	11th to 20th	Day	51% 4 8% 20% 16% 2	2254
	21st to end	Day	57% 3 9% 17% 11% 3	2394
May	1st to 10th	Day	59% 2 7% 20% 11% 1	4273
	11th to 20th	Day	54% 2 13% 21% 9% 1	4402
	21st to end	Day	43% 3 11% 29% 12% 1	4837
June	1st to 10th	Day	52% 5% 12% 20% 10% 1	2660
	11th to 20th	Day	47% 5% 12% 22% 13% 2	2660
	21st to end	Day	50% 5% 13% 20% 11% 1	2660
July	1st to 10th	Day	42% 6% 15% 24% 13%	4370
	11th to 20th	Day	39% 6% 15% 31% 9%	4365
	21st to end	Day	44% 6% 13% 25% 11%	4661
August	1st to 10th	Day	44% 5% 16% 25% 10%	2632
	11th to 20th	Day	43% 5% 16% 26% 10%	2239
	21st to end	Day	41% 5% 12% 27% 13% 1	2376
September	1st to 10th	Day	39% 6% 11% 30% 12% 1	2160
	11th to 20th	Day	38% 3 10% 30% 18% 1	2080
	21st to end	Day	42% 4 13% 25% 13% 2	1980
October	1st to 10th	Day	54% 4 8% 21% 12% 1	1872
	11th to 20th	Day	49% 4 14% 25% 8% 1	1788
	21st to end	Day	59% 4 11% 16% 9% 1	1782
November	1st to 10th	Day	47% 4 15% 21% 12%	1671
	11th to 20th	Day	51% 5% 11% 18% 13% 3	1705
	21st to end	Day	55% 4 15% 18% 7% 1	1520
December	1st to 10th	Day	65% 3 11% 15% 5% 1	1520
	11th to 20th	Day	58% 3 14% 16% 8% 1	1906
	21st to end	Day	67% 3 7% 16% 8%	2772
January	1st to 10th	Night	57% 3 14% 18% 8%	4429
	11th to 20th	Night	67% 3 10% 12% 8% 1	4440
	21st to end	Night	63% 2 8% 17% 8% 1	4852
February	1st to 10th	Night	58% 5% 11% 17% 8% 1	2470
	11th to 20th	Night	53% 4 10% 20% 13% 1	2272
	21st to end	Night	53% 2 11% 21% 10% 2	1884
March	1st to 10th	Night	60% 2 8% 18% 11% 1	3734
	11th to 20th	Night	55% 2 11% 19% 11% 2	3672
	21st to end	Night	53% 3 5% 18% 18% 3	3471
April	1st to 10th	Night	52% 4 8% 22% 13% 2	1900
	11th to 20th	Night	51% 3 10% 21% 13% 1	1875
	21st to end	Night	50% 4 9% 20% 14% 3	1786
May	1st to 10th	Night	59% 2 9% 17% 11% 1	2716
	11th to 20th	Night	57% 3 11% 19% 10% 1	2496
	21st to end	Night	44% 3 14% 23% 15% 2	2739
June	1st to 10th	Night	46% 4 15% 22% 12% 1	1520
	11th to 20th	Night	43% 4 16% 22% 13% 2	1520
	21st to end	Night	46% 5% 13% 25% 10% 1	1520
July	1st to 10th	Night	42% 6% 15% 23% 13% 1	2480
	11th to 20th	Night	38% 6% 16% 28% 12%	2472
	21st to end	Night	38% 7% 14% 29% 11% 1	2651
August	1st to 10th	Night	36% 6% 18% 29% 12% 1	1502
	11th to 20th	Night	40% 6% 15% 29% 11%	1738
	21st to end	Night	35% 5% 15% 31% 13% 1	1980
September	1st to 10th	Night	37% 6% 15% 31% 11% 1	1800
	11th to 20th	Night	36% 4 12% 31% 18% 1	1880
	21st to end	Night	40% 3 13% 28% 13% 2	1980
October	1st to 10th	Night	52% 3 11% 21% 12% 1	2086
	11th to 20th	Night	48% 4 14% 25% 8% 1	2170
	21st to end	Night	56% 4 13% 17% 9% 1	2574
November	1st to 10th	Night	48% 4 13% 21% 12% 2	2407
	11th to 20th	Night	50% 4 12% 21% 11% 3	2474
	21st to end	Night	52% 5% 15% 20% 8% 1	2660
December	1st to 10th	Night	62% 4 12% 17% 4	2660
	11th to 20th	Night	57% 4 11% 17% 10% 1	3288
	21st to end	Night	66% 3 9% 18% 5%	4884

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	23% 17% 33% 19% 8%	180
	11th to 20th	Day	24% 28% 31% 13% 2 1	180
	21st to end	Day	16% 23% 38% 18% 5%	206
February	1st to 10th	Day	27% 37% 25% 9% 1	270
	11th to 20th	Day	23% 31% 32% 12% 2	404
	21st to end	Day	30% 18% 33% 16% 3	382
March	1st to 10th	Day	25% 20% 33% 18% 4	460
	11th to 20th	Day	29% 22% 30% 14% 4 1	460
	21st to end	Day	30% 24% 22% 15% 8% 1	506
April	1st to 10th	Day	34% 17% 28% 14% 6%	460
	11th to 20th	Day	31% 21% 24% 14% 7% 3	452
	21st to end	Day	33% 16% 32% 11% 6% 2	460
May	1st to 10th	Day	29% 18% 29% 13% 7% 3	463
	11th to 20th	Day	20% 16% 32% 23% 6% 2	487
	21st to end	Day	19% 14% 33% 23% 10% 2	529
June	1st to 10th	Day	23% 15% 31% 20% 9% 2	490
	11th to 20th	Day	17% 14% 37% 22% 9% 1	490
	21st to end	Day	22% 13% 34% 20% 8% 2	490
July	1st to 10th	Day	14% 9% 29% 32% 13% 3	485
	11th to 20th	Day	16% 8% 34% 27% 13% 2	484
	21st to end	Day	14% 9% 34% 30% 10% 2	532
August	1st to 10th	Day	12% 10% 29% 29% 14% 6%	486
	11th to 20th	Day	15% 8% 29% 27% 15% 7%	456
	21st to end	Day	13% 13% 28% 25% 15% 6%	495
September	1st to 10th	Day	15% 8% 28% 26% 13% 9%	450
	11th to 20th	Day	14% 12% 26% 21% 15% 11%	450
	21st to end	Day	20% 10% 29% 23% 12% 6%	450
October	1st to 10th	Day	28% 15% 23% 16% 14% 4	450
	11th to 20th	Day	21% 18% 27% 24% 10% 1	444
	21st to end	Day	30% 14% 28% 22% 6%	396
November	1st to 10th	Day	22% 19% 24% 24% 11% 1	365
	11th to 20th	Day	24% 21% 28% 19% 7% 1	365
	21st to end	Day	23% 23% 33% 17% 4	180
December	1st to 10th	Day	26% 24% 27% 18% 4 1	180
	11th to 20th	Day	27% 26% 33% 13% 1	180
	21st to end	Day	29% 23% 30% 16% 3	198
January	1st to 10th	Night	21% 18% 33% 24% 4	760
	11th to 20th	Night	22% 18% 32% 24% 3	760
	21st to end	Night	16% 20% 33% 25% 6%	836
February	1st to 10th	Night	19% 18% 37% 23% 2	760
	11th to 20th	Night	18% 21% 36% 22% 3	743
	21st to end	Night	23% 19% 34% 21% 3	628
March	1st to 10th	Night	22% 17% 33% 25% 3	760
	11th to 20th	Night	25% 18% 28% 24% 5%	760
	21st to end	Night	23% 16% 28% 25% 7% 1	836
April	1st to 10th	Night	25% 14% 30% 26% 5%	760
	11th to 20th	Night	24% 20% 27% 21% 7% 1	751
	21st to end	Night	27% 14% 28% 23% 8%	646
May	1st to 10th	Night	30% 12% 25% 22% 10%	498
	11th to 20th	Night	19% 13% 27% 31% 9% 1	374
	21st to end	Night	17% 9% 25% 36% 14% 1	411
June	1st to 10th	Night	22% 6% 27% 31% 14%	380
	11th to 20th	Night	17% 6% 24% 37% 15%	380
	21st to end	Night	19% 7% 26% 34% 13% 1	380
July	1st to 10th	Night	14% 4 20% 42% 19% 2	370
	11th to 20th	Night	12% 4 21% 41% 19% 2	368
	21st to end	Night	13% 5% 20% 44% 18% 1	416
August	1st to 10th	Night	12% 3 19% 42% 23% 1	378
	11th to 20th	Night	14% 4 18% 39% 23% 3	644
	21st to end	Night	16% 5% 19% 37% 21% 2	792
September	1st to 10th	Night	14% 6% 22% 38% 17% 3	720
	11th to 20th	Night	16% 8% 21% 30% 21% 4	720
	21st to end	Night	18% 7% 27% 27% 17% 3	720
October	1st to 10th	Night	24% 12% 20% 27% 16% 2	720
	11th to 20th	Night	20% 12% 24% 31% 12% 1	720
	21st to end	Night	27% 13% 27% 27% 8%	792
November	1st to 10th	Night	20% 15% 29% 28% 8% 1	740
	11th to 20th	Night	23% 18% 26% 24% 8% 2	760
	21st to end	Night	21% 18% 29% 25% 7%	760
December	1st to 10th	Night	26% 17% 33% 21% 4	760
	11th to 20th	Night	25% 18% 28% 23% 6%	760
	21st to end	Night	26% 16% 33% 22% 3	836

Page generated at 2024-08-12 09:52:54. Version ac07

Copyright © 2024 Attilla Danko.