Glens Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Glens Falls clear sky chart from 2005-11-06 to 2024-11-05.

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% 8% 3 7% 5% 5% 5% 4 6% 7% 33%	101406
	Night	17% 9% 3 8% 5% 4 4 4 5% 6% 34%	97653
Transparency	Day	47% 8% 13% 20% 10% 1	104902
	Night	49% 8% 13% 19% 10% 1	102246
Seeing	Day	21% 15% 30% 22% 10% 3	14781
	Night	20% 11% 30% 29% 9% 1	23793

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	12% 12% 4 11% 6% 6% 5% 4 6% 5% 28%	2517
	11th to 20th	Day	15% 14% 7% 11% 7% 5% 5% 4 4 5% 23%	2520
	21st to end	Day	16% 13% 4 11% 6% 6% 5% 4 5% 6% 23%	2813
February	1st to 10th	Day	13% 13% 3 9% 6% 5% 5% 4 7% 7% 28%	1710
	11th to 20th	Day	12% 14% 5% 10% 5% 5% 5% 4 6% 5% 29%	1814
	21st to end	Day	19% 11% 4 8% 5% 4 4 3 5% 5% 32%	1570
March	1st to 10th	Day	22% 13% 5% 10% 5% 4 3 3 3 5% 27%	3116
	11th to 20th	Day	13% 11% 4 10% 5% 5% 5% 3 5% 7% 31%	3278
	21st to end	Day	18% 10% 3 7% 5% 4 4 3 3 5% 37%	4166
April	1st to 10th	Day	19% 10% 4 7% 4 4 3 3 5% 6% 35%	2280
	11th to 20th	Day	17% 7% 2 8% 6% 4 4 4 5% 6% 37%	2254
	21st to end	Day	21% 8% 3 7% 5% 5% 4 4 5% 6% 32%	2387
May	1st to 10th	Day	23% 9% 3 8% 4 4 4 4 5% 6% 29%	4217
	11th to 20th	Day	17% 7% 3 8% 5% 5% 5% 4 6% 7% 33%	4398
	21st to end	Day	11% 5% 2 6% 4 5% 5% 4 6% 8% 43%	4837
June	1st to 10th	Day	15% 7% 3 7% 6% 6% 5% 5% 7% 8% 31%	2660
	11th to 20th	Day	16% 6% 3 5% 5% 5% 5% 5% 6% 9% 35%	2660
	21st to end	Day	16% 7% 2 8% 6% 5% 6% 5% 6% 9% 31%	2660
July	1st to 10th	Day	10% 6% 2 7% 4 5% 5% 5% 8% 10% 38%	4440
	11th to 20th	Day	9% 6% 2 6% 5% 6% 6% 6% 9% 12% 33%	4440
	21st to end	Day	13% 5% 2 7% 5% 6% 6% 5% 7% 9% 35%	4814
August	1st to 10th	Day	15% 6% 2 7% 6% 6% 5% 5% 6% 9% 34%	4423
	11th to 20th	Day	13% 6% 3 7% 5% 6% 6% 5% 8% 10% 31%	3774
	21st to end	Day	11% 6% 3 7% 4 5% 6% 5% 7% 9% 37%	4180
September	1st to 10th	Day	13% 4 1 5% 4 4 6% 4 6% 8% 45%	2280
	11th to 20th	Day	14% 5% 1 4 4 4 3 4 5% 7% 48%	2189
	21st to end	Day	15% 5% 3 5% 4 4 5% 4 5% 7% 41%	2090
October	1st to 10th	Day	20% 9% 2 8% 5% 5% 4 4 5% 4 34%	1987
	11th to 20th	Day	15% 8% 2 7% 4 4 5% 4 6% 8% 38%	1891
	21st to end	Day	24% 8% 3 7% 5% 6% 4 3 5% 6% 30%	1881
November	1st to 10th	Day	12% 9% 3 8% 5% 4 4 3 6% 7% 39%	1708
	11th to 20th	Day	16% 9% 3 6% 5% 5% 5% 4 6% 6% 35%	1710
	21st to end	Day	18% 8% 3 7% 6% 5% 5% 4 5% 7% 33%	1544
December	1st to 10th	Day	20% 13% 5% 9% 5% 5% 4 3 5% 7% 24%	1520
	11th to 20th	Day	22% 11% 3 7% 5% 5% 5% 3 3 5% 31%	1906
	21st to end	Day	25% 17% 5% 8% 5% 3 3 2 3 4 23%	2772
January	1st to 10th	Night	15% 12% 5% 9% 5% 5% 4 3 5% 6% 31%	4429
	11th to 20th	Night	13% 11% 5% 13% 7% 7% 5% 4 5% 5% 25%	4440
	21st to end	Night	21% 15% 4 9% 5% 4 4 3 4 4 26%	4841
February	1st to 10th	Night	13% 13% 5% 10% 7% 5% 6% 4 6% 6% 26%	2470
	11th to 20th	Night	11% 11% 4 9% 6% 5% 5% 4 6% 6% 32%	2251
	21st to end	Night	16% 9% 4 9% 5% 4 5% 4 5% 5% 33%	1884
March	1st to 10th	Night	25% 11% 3 7% 4 4 4 4 5% 5% 29%	3724
	11th to 20th	Night	15% 12% 3 8% 5% 5% 5% 4 4 6% 33%	3677
	21st to end	Night	17% 13% 4 9% 4 4 4 3 4 4 35%	3466
April	1st to 10th	Night	20% 7% 3 7% 5% 4 4 3 4 6% 36%	1900
	11th to 20th	Night	19% 9% 3 6% 5% 5% 3 3 5% 7% 36%	1875
	21st to end	Night	19% 9% 2 6% 4 4 4 3 5% 5% 38%	1791
May	1st to 10th	Night	24% 10% 3 7% 5% 4 4 4 5% 6% 29%	2752
	11th to 20th	Night	18% 10% 4 8% 6% 4 5% 3 5% 6% 30%	2495
	21st to end	Night	13% 6% 2 6% 5% 4 5% 5% 5% 8% 41%	2738
June	1st to 10th	Night	18% 6% 2 5% 5% 5% 5% 4 7% 7% 36%	1520
	11th to 20th	Night	17% 7% 3 6% 4 3 4 3 6% 8% 39%	1520
	21st to end	Night	16% 5% 2 6% 5% 5% 5% 4 6% 7% 39%	1520
July	1st to 10th	Night	11% 6% 3 7% 5% 5% 5% 5% 6% 8% 38%	2520
	11th to 20th	Night	13% 6% 2 7% 4 5% 5% 4 6% 9% 40%	2520
	21st to end	Night	13% 6% 2 6% 5% 6% 4 4 6% 8% 39%	2739
August	1st to 10th	Night	18% 8% 3 7% 4 4 4 3 6% 7% 36%	2506
	11th to 20th	Night	15% 6% 3 7% 4 4 5% 5% 7% 8% 35%	3019
	21st to end	Night	10% 5% 2 5% 5% 4 6% 6% 8% 9% 40%	3476
September	1st to 10th	Night	13% 6% 2 6% 4 4 4 4 5% 7% 45%	1900
	11th to 20th	Night	13% 5% 1 5% 3 3 3 3 5% 7% 51%	1990
	21st to end	Night	15% 5% 2 5% 4 4 5% 4 6% 6% 45%	2090
October	1st to 10th	Night	20% 9% 3 7% 5% 5% 4 4 5% 5% 34%	2190
	11th to 20th	Night	15% 7% 3 7% 5% 5% 4 4 6% 6% 38%	2289
	21st to end	Night	24% 8% 3 7% 5% 4 4 3 5% 6% 31%	2717
November	1st to 10th	Night	14% 8% 2 9% 4 5% 5% 3 4 6% 40%	2470
	11th to 20th	Night	19% 8% 3 6% 4 3 3 3 6% 6% 38%	2470
	21st to end	Night	16% 10% 3 7% 5% 4 5% 4 5% 7% 35%	2632
December	1st to 10th	Night	20% 13% 4 8% 6% 4 5% 4 5% 5% 27%	2660
	11th to 20th	Night	23% 10% 3 7% 5% 5% 5% 3 5% 6% 30%	3288
	21st to end	Night	26% 17% 5% 7% 5% 4 4 3 3 5% 23%	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	52% 11% 13% 19% 5% 1	2518
	11th to 20th	Day	61% 9% 12% 12% 5% 1	2520
	21st to end	Day	61% 9% 12% 13% 5% 1	2813
February	1st to 10th	Day	55% 9% 14% 15% 6% 1	1710
	11th to 20th	Day	56% 6% 12% 15% 9% 1	1823
	21st to end	Day	54% 6% 12% 15% 11% 1	1570
March	1st to 10th	Day	59% 7% 11% 13% 8% 1	3119
	11th to 20th	Day	47% 12% 17% 13% 9% 2	3278
	21st to end	Day	49% 6% 8% 17% 17% 3	4166
April	1st to 10th	Day	50% 6% 10% 20% 11% 3	2280
	11th to 20th	Day	47% 8% 10% 19% 14% 2	2254
	21st to end	Day	51% 8% 10% 16% 12% 3	2387
May	1st to 10th	Day	52% 9% 11% 18% 9% 1	4231
	11th to 20th	Day	46% 12% 15% 17% 9% 1	4402
	21st to end	Day	36% 10% 15% 25% 14% 1	4837
June	1st to 10th	Day	47% 10% 15% 17% 10% 1	2660
	11th to 20th	Day	44% 9% 14% 19% 13% 1	2660
	21st to end	Day	48% 8% 14% 18% 11%	2660
July	1st to 10th	Day	39% 8% 15% 24% 14% 1	4370
	11th to 20th	Day	39% 8% 17% 28% 9%	4365
	21st to end	Day	44% 6% 16% 23% 10% 1	4661
August	1st to 10th	Day	46% 7% 16% 19% 11% 1	4409
	11th to 20th	Day	47% 8% 15% 25% 6%	3811
	21st to end	Day	42% 6% 15% 27% 11% 1	4180
September	1st to 10th	Day	37% 8% 13% 29% 12% 1	2280
	11th to 20th	Day	35% 7% 11% 27% 18% 1	2189
	21st to end	Day	40% 9% 13% 24% 12% 1	2090
October	1st to 10th	Day	48% 6% 7% 25% 14% 1	3299
	11th to 20th	Day	41% 6% 13% 26% 14% 1	3119
	21st to end	Day	40% 6% 13% 29% 11% 1	3081
November	1st to 10th	Day	42% 8% 15% 23% 11% 1	1708
	11th to 20th	Day	47% 8% 13% 17% 13% 1	1710
	21st to end	Day	51% 8% 17% 17% 6% 1	1544
December	1st to 10th	Day	59% 8% 14% 13% 6% 1	1520
	11th to 20th	Day	55% 7% 15% 16% 5% 1	1906
	21st to end	Day	66% 6% 9% 12% 7%	2772
January	1st to 10th	Night	51% 10% 16% 14% 8% 1	4429
	11th to 20th	Night	59% 9% 12% 13% 6% 1	4440
	21st to end	Night	61% 6% 12% 13% 6% 1	4841
February	1st to 10th	Night	57% 8% 13% 15% 6% 1	2470
	11th to 20th	Night	51% 8% 12% 18% 9% 1	2253
	21st to end	Night	51% 7% 14% 18% 8% 2	1884
March	1st to 10th	Night	53% 10% 10% 17% 9% 1	3734
	11th to 20th	Night	49% 9% 14% 18% 8% 2	3678
	21st to end	Night	52% 5% 8% 15% 17% 3	3466
April	1st to 10th	Night	50% 6% 11% 20% 11% 2	1900
	11th to 20th	Night	49% 6% 10% 21% 13% 1	1875
	21st to end	Night	48% 7% 10% 18% 14% 4	1791
May	1st to 10th	Night	52% 10% 11% 15% 10% 1	2758
	11th to 20th	Night	52% 11% 12% 16% 8% 1	2496
	21st to end	Night	39% 11% 14% 19% 16% 2	2739
June	1st to 10th	Night	43% 9% 14% 21% 10% 2	1520
	11th to 20th	Night	41% 9% 15% 22% 12% 1	1520
	21st to end	Night	41% 11% 13% 21% 12% 1	1520
July	1st to 10th	Night	43% 6% 16% 20% 14% 1	2480
	11th to 20th	Night	43% 7% 15% 22% 14%	2472
	21st to end	Night	43% 6% 12% 27% 11% 1	2651
August	1st to 10th	Night	48% 7% 15% 22% 8%	2496
	11th to 20th	Night	45% 6% 19% 21% 9%	3048
	21st to end	Night	39% 6% 15% 29% 11%	3476
September	1st to 10th	Night	37% 7% 14% 27% 13% 1	1900
	11th to 20th	Night	33% 7% 13% 29% 17% 1	1990
	21st to end	Night	39% 7% 13% 24% 15% 2	2090
October	1st to 10th	Night	52% 5% 10% 20% 12% 1	3658
	11th to 20th	Night	37% 6% 13% 26% 17% 1	3800
	21st to end	Night	46% 5% 12% 28% 9% 1	4467
November	1st to 10th	Night	45% 6% 13% 21% 12% 2	2470
	11th to 20th	Night	46% 7% 13% 21% 11% 2	2470
	21st to end	Night	48% 8% 17% 19% 7%	2632
December	1st to 10th	Night	58% 8% 14% 16% 4	2660
	11th to 20th	Night	55% 8% 14% 15% 8%	3288
	21st to end	Night	63% 8% 10% 15% 4	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	24% 20% 30% 18% 7% 1	180
	11th to 20th	Day	28% 26% 31% 13% 1 1	180
	21st to end	Day	21% 20% 35% 17% 5% 1	211
February	1st to 10th	Day	27% 29% 30% 12% 1	270
	11th to 20th	Day	26% 25% 35% 12% 2	422
	21st to end	Day	28% 18% 35% 16% 3	382
March	1st to 10th	Day	26% 15% 34% 21% 4 1	460
	11th to 20th	Day	28% 21% 31% 15% 5%	460
	21st to end	Day	29% 21% 26% 15% 7% 2	506
April	1st to 10th	Day	31% 19% 26% 16% 7% 1	460
	11th to 20th	Day	29% 23% 26% 13% 8% 2	452
	21st to end	Day	29% 17% 32% 15% 7% 2	460
May	1st to 10th	Day	30% 16% 29% 14% 9% 2	463
	11th to 20th	Day	17% 15% 35% 23% 8% 2	487
	21st to end	Day	14% 16% 29% 27% 11% 3	529
June	1st to 10th	Day	16% 15% 31% 24% 11% 2	490
	11th to 20th	Day	17% 13% 31% 26% 10% 3	490
	21st to end	Day	18% 14% 32% 24% 10% 2	490
July	1st to 10th	Day	13% 8% 30% 29% 16% 3	485
	11th to 20th	Day	12% 8% 32% 31% 15% 4	484
	21st to end	Day	14% 5% 36% 31% 12% 2	532
August	1st to 10th	Day	12% 8% 27% 30% 17% 5%	486
	11th to 20th	Day	15% 6% 28% 28% 18% 6%	479
	21st to end	Day	11% 9% 26% 31% 16% 7%	539
September	1st to 10th	Day	12% 10% 23% 30% 16% 8%	490
	11th to 20th	Day	14% 11% 23% 22% 18% 12%	490
	21st to end	Day	17% 9% 29% 24% 14% 7%	490
October	1st to 10th	Day	24% 11% 26% 20% 13% 5%	490
	11th to 20th	Day	17% 17% 31% 23% 10% 2	485
	21st to end	Day	29% 14% 26% 24% 6% 1	429
November	1st to 10th	Day	21% 16% 26% 24% 13% 1	378
	11th to 20th	Day	28% 16% 29% 21% 5% 1	370
	21st to end	Day	25% 18% 35% 17% 4	204
December	1st to 10th	Day	24% 22% 32% 17% 6%	180
	11th to 20th	Day	32% 18% 33% 14% 2	180
	21st to end	Day	27% 19% 32% 18% 4	198
January	1st to 10th	Night	21% 14% 36% 26% 3	760
	11th to 20th	Night	24% 16% 33% 24% 2	760
	21st to end	Night	18% 13% 38% 27% 4	836
February	1st to 10th	Night	20% 16% 40% 23% 2	760
	11th to 20th	Night	17% 18% 41% 22% 2	743
	21st to end	Night	23% 15% 36% 21% 4	628
March	1st to 10th	Night	23% 16% 35% 24% 3	760
	11th to 20th	Night	24% 15% 33% 23% 4	760
	21st to end	Night	22% 16% 33% 22% 7%	836
April	1st to 10th	Night	25% 16% 31% 24% 4	760
	11th to 20th	Night	23% 17% 31% 22% 7%	751
	21st to end	Night	25% 15% 29% 25% 6%	651
May	1st to 10th	Night	26% 12% 27% 27% 9%	527
	11th to 20th	Night	19% 10% 36% 29% 6% 1	374
	21st to end	Night	14% 10% 25% 37% 13% 1	411
June	1st to 10th	Night	20% 3 27% 37% 12% 1	380
	11th to 20th	Night	17% 7% 27% 38% 11%	380
	21st to end	Night	15% 5% 27% 42% 10%	380
July	1st to 10th	Night	13% 4 21% 45% 15% 2	370
	11th to 20th	Night	14% 3 18% 46% 18% 1	368
	21st to end	Night	13% 2 21% 47% 16% 1	416
August	1st to 10th	Night	13% 2 19% 47% 19% 1	378
	11th to 20th	Night	15% 4 20% 37% 21% 3	696
	21st to end	Night	14% 5% 19% 40% 22% 1	836
September	1st to 10th	Night	15% 4 23% 39% 17% 3	760
	11th to 20th	Night	15% 6% 22% 31% 22% 5%	760
	21st to end	Night	17% 6% 24% 33% 18% 2	760
October	1st to 10th	Night	24% 9% 22% 28% 15% 2	760
	11th to 20th	Night	20% 9% 26% 34% 10% 1	760
	21st to end	Night	28% 11% 28% 28% 6%	836
November	1st to 10th	Night	17% 12% 33% 30% 8%	760
	11th to 20th	Night	21% 13% 33% 25% 7% 1	760
	21st to end	Night	21% 13% 35% 25% 6% 1	760
December	1st to 10th	Night	27% 13% 32% 24% 4	760
	11th to 20th	Night	27% 12% 32% 26% 4	760
	21st to end	Night	27% 14% 34% 23% 2	836

Page generated at 2024-11-03 02:11:11. Version ac07

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