Rensselaerville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rensselaerville clear sky chart from 2005-11-06 to 2024-11-04.

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	15% 9% 3 8% 5% 5% 5% 4 6% 7% 33%	101404
	Night	15% 9% 3 7% 5% 5% 5% 4 6% 7% 35%	97622
Transparency	Day	47% 7% 13% 21% 11% 1	104910
	Night	46% 7% 13% 22% 12% 1	102205
Seeing	Day	24% 16% 29% 20% 9% 3	14823
	Night	23% 16% 29% 23% 8% 1	23893

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% 10% 4 10% 5% 6% 6% 5% 5% 7% 29%	2517
	11th to 20th	Day	12% 14% 5% 12% 6% 6% 6% 4 5% 5% 25%	2520
	21st to end	Day	16% 15% 6% 11% 7% 4 5% 3 5% 5% 22%	2909
February	1st to 10th	Day	13% 13% 4 9% 6% 6% 6% 5% 6% 6% 25%	1710
	11th to 20th	Day	10% 9% 5% 11% 7% 5% 5% 4 6% 7% 31%	1808
	21st to end	Day	16% 12% 3 8% 5% 4 4 4 5% 6% 31%	1570
March	1st to 10th	Day	22% 12% 4 9% 5% 4 4 3 4 6% 28%	3116
	11th to 20th	Day	10% 10% 5% 10% 7% 6% 5% 4 6% 6% 31%	3338
	21st to end	Day	18% 10% 3 7% 5% 4 4 3 4 5% 36%	4130
April	1st to 10th	Day	16% 11% 4 8% 6% 5% 4 3 5% 6% 34%	2280
	11th to 20th	Day	16% 10% 3 7% 5% 5% 5% 3 5% 5% 37%	2254
	21st to end	Day	19% 9% 2 8% 5% 5% 5% 4 5% 6% 33%	2342
May	1st to 10th	Day	23% 10% 3 7% 4 5% 4 3 5% 6% 28%	4218
	11th to 20th	Day	18% 8% 3 7% 5% 5% 5% 4 6% 7% 32%	4398
	21st to end	Day	11% 5% 2 6% 5% 5% 6% 5% 8% 10% 38%	4837
June	1st to 10th	Day	15% 7% 3 8% 6% 5% 6% 4 7% 9% 31%	2660
	11th to 20th	Day	15% 5% 2 7% 6% 5% 6% 5% 6% 9% 33%	2660
	21st to end	Day	15% 7% 2 7% 6% 5% 5% 5% 6% 8% 33%	2660
July	1st to 10th	Day	10% 6% 2 7% 6% 6% 7% 5% 7% 10% 35%	4440
	11th to 20th	Day	9% 5% 2 6% 5% 6% 6% 6% 8% 11% 35%	4440
	21st to end	Day	13% 6% 3 8% 6% 6% 6% 5% 7% 8% 33%	4814
August	1st to 10th	Day	16% 6% 2 8% 5% 5% 6% 4 6% 7% 33%	4360
	11th to 20th	Day	12% 7% 3 7% 6% 6% 5% 4 8% 10% 32%	3739
	21st to end	Day	12% 5% 2 6% 4 5% 6% 5% 8% 10% 38%	4180
September	1st to 10th	Day	13% 7% 2 6% 4 4 5% 4 5% 7% 42%	2280
	11th to 20th	Day	13% 5% 2 6% 3 4 4 3 5% 7% 48%	2207
	21st to end	Day	16% 6% 2 5% 4 4 5% 4 7% 8% 39%	2090
October	1st to 10th	Day	17% 9% 3 7% 4 5% 5% 4 5% 5% 36%	1962
	11th to 20th	Day	14% 8% 3 7% 5% 4 4 4 5% 7% 40%	1900
	21st to end	Day	19% 9% 3 7% 6% 4 5% 4 5% 6% 31%	1910
November	1st to 10th	Day	12% 10% 3 5% 4 4 3 4 4 6% 42%	1698
	11th to 20th	Day	14% 9% 3 8% 5% 5% 6% 4 4 6% 35%	1710
	21st to end	Day	15% 10% 4 6% 6% 5% 6% 4 5% 6% 33%	1549
December	1st to 10th	Day	15% 12% 4 11% 7% 6% 6% 4 5% 5% 23%	1520
	11th to 20th	Day	20% 11% 3 6% 6% 5% 4 4 4 7% 30%	1906
	21st to end	Day	18% 13% 7% 10% 5% 4 5% 4 5% 7% 20%	2772
January	1st to 10th	Night	14% 10% 4 7% 5% 4 4 4 6% 8% 33%	4429
	11th to 20th	Night	12% 12% 4 10% 7% 5% 6% 5% 6% 7% 27%	4440
	21st to end	Night	19% 12% 5% 11% 6% 6% 4 3 4 5% 23%	4745
February	1st to 10th	Night	13% 13% 4 8% 7% 4 5% 4 6% 7% 29%	2470
	11th to 20th	Night	11% 9% 4 11% 7% 7% 5% 5% 6% 8% 29%	2256
	21st to end	Night	16% 9% 3 7% 6% 5% 5% 4 6% 7% 31%	1884
March	1st to 10th	Night	20% 10% 3 7% 5% 4 4 4 6% 6% 30%	3724
	11th to 20th	Night	11% 9% 4 8% 7% 5% 5% 5% 6% 6% 33%	3617
	21st to end	Night	14% 11% 3 9% 6% 5% 5% 3 5% 6% 34%	3500
April	1st to 10th	Night	15% 10% 3 9% 7% 6% 5% 4 6% 7% 29%	1900
	11th to 20th	Night	19% 8% 2 7% 5% 5% 4 3 5% 7% 36%	1875
	21st to end	Night	18% 8% 3 7% 4 3 5% 4 6% 5% 37%	1837
May	1st to 10th	Night	23% 10% 3 7% 4 5% 4 4 5% 7% 30%	2752
	11th to 20th	Night	16% 9% 4 9% 5% 5% 4 4 6% 6% 33%	2495
	21st to end	Night	11% 6% 2 8% 5% 4 5% 4 7% 9% 37%	2738
June	1st to 10th	Night	15% 7% 3 6% 5% 4 4 4 5% 7% 40%	1520
	11th to 20th	Night	14% 5% 2 5% 4 3 4 4 8% 10% 40%	1520
	21st to end	Night	10% 5% 1 5% 5% 4 4 4 7% 11% 43%	1520
July	1st to 10th	Night	9% 6% 2 7% 6% 4 5% 5% 7% 8% 42%	2520
	11th to 20th	Night	13% 5% 3 5% 4 4 5% 4 7% 9% 43%	2520
	21st to end	Night	14% 6% 2 6% 4 5% 5% 4 6% 7% 41%	2739
August	1st to 10th	Night	18% 6% 2 6% 4 4 5% 4 6% 7% 38%	2565
	11th to 20th	Night	14% 7% 3 7% 4 4 4 4 5% 7% 42%	3057
	21st to end	Night	12% 5% 1 5% 3 3 4 3 5% 8% 49%	3476
September	1st to 10th	Night	12% 6% 2 5% 5% 4 5% 3 6% 6% 45%	1900
	11th to 20th	Night	13% 4 1 4 3 3 4 2 6% 6% 53%	1972
	21st to end	Night	14% 5% 2 6% 4 5% 4 4 4 7% 45%	2090
October	1st to 10th	Night	20% 7% 2 7% 3 4 4 3 5% 6% 38%	2213
	11th to 20th	Night	15% 7% 2 6% 4 4 4 4 6% 7% 41%	2280
	21st to end	Night	20% 8% 3 7% 4 4 4 4 6% 6% 34%	2687
November	1st to 10th	Night	14% 10% 2 6% 4 4 5% 3 5% 7% 42%	2453
	11th to 20th	Night	16% 9% 3 6% 5% 5% 5% 4 6% 7% 35%	2470
	21st to end	Night	13% 9% 3 7% 5% 5% 5% 4 6% 7% 36%	2626
December	1st to 10th	Night	15% 10% 4 8% 5% 6% 6% 4 6% 9% 26%	2660
	11th to 20th	Night	17% 9% 3 8% 6% 5% 5% 5% 7% 6% 30%	3288
	21st to end	Night	22% 11% 6% 9% 5% 5% 4 3 5% 7% 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	50% 6% 15% 21% 6% 1	2518
	11th to 20th	Day	59% 6% 11% 15% 7% 1	2520
	21st to end	Day	60% 7% 11% 15% 5% 1	2909
February	1st to 10th	Day	57% 6% 13% 14% 9% 1	1710
	11th to 20th	Day	50% 7% 9% 22% 10% 2	1817
	21st to end	Day	53% 6% 11% 17% 12% 1	1570
March	1st to 10th	Day	57% 5% 11% 16% 9% 1	3119
	11th to 20th	Day	48% 7% 16% 18% 9% 2	3338
	21st to end	Day	49% 5% 6% 17% 20% 3	4130
April	1st to 10th	Day	51% 4 10% 21% 12% 2	2280
	11th to 20th	Day	48% 5% 11% 20% 15% 2	2254
	21st to end	Day	51% 5% 11% 18% 13% 3	2342
May	1st to 10th	Day	54% 8% 9% 17% 11% 1	4232
	11th to 20th	Day	48% 7% 14% 21% 8% 1	4402
	21st to end	Day	36% 10% 15% 25% 13% 1	4837
June	1st to 10th	Day	47% 8% 14% 19% 12% 1	2660
	11th to 20th	Day	45% 8% 15% 21% 11% 1	2660
	21st to end	Day	46% 7% 15% 21% 11% 1	2660
July	1st to 10th	Day	41% 8% 14% 23% 12% 1	4370
	11th to 20th	Day	39% 8% 17% 24% 11% 1	4365
	21st to end	Day	47% 7% 14% 20% 12% 1	4661
August	1st to 10th	Day	48% 8% 14% 19% 10% 1	4346
	11th to 20th	Day	44% 8% 17% 26% 5%	3775
	21st to end	Day	36% 7% 14% 31% 10% 1	4180
September	1st to 10th	Day	40% 6% 13% 25% 16% 1	2280
	11th to 20th	Day	35% 6% 13% 26% 19% 2	2207
	21st to end	Day	40% 7% 13% 24% 14% 2	2090
October	1st to 10th	Day	42% 6% 10% 21% 20% 1	3261
	11th to 20th	Day	35% 5% 11% 26% 18% 4	3140
	21st to end	Day	35% 7% 15% 27% 12% 3	3122
November	1st to 10th	Day	42% 6% 13% 25% 13% 2	1698
	11th to 20th	Day	48% 5% 13% 19% 14% 1	1710
	21st to end	Day	50% 6% 15% 20% 8% 1	1549
December	1st to 10th	Day	60% 6% 12% 15% 7% 1	1520
	11th to 20th	Day	52% 5% 16% 18% 8% 1	1906
	21st to end	Day	63% 7% 11% 15% 5%	2772
January	1st to 10th	Night	46% 8% 16% 19% 10% 1	4429
	11th to 20th	Night	54% 6% 13% 16% 9% 1	4440
	21st to end	Night	61% 6% 10% 15% 6% 1	4745
February	1st to 10th	Night	53% 7% 12% 18% 9% 1	2470
	11th to 20th	Night	51% 7% 12% 19% 11% 1	2258
	21st to end	Night	50% 6% 13% 20% 9% 2	1884
March	1st to 10th	Night	53% 6% 11% 19% 10% 1	3734
	11th to 20th	Night	47% 7% 14% 23% 8% 1	3618
	21st to end	Night	49% 6% 8% 17% 17% 3	3500
April	1st to 10th	Night	51% 5% 13% 19% 10% 2	1900
	11th to 20th	Night	47% 6% 12% 19% 15% 1	1875
	21st to end	Night	46% 6% 12% 19% 15% 3	1837
May	1st to 10th	Night	54% 7% 11% 16% 11% 2	2758
	11th to 20th	Night	49% 8% 12% 21% 8% 1	2496
	21st to end	Night	39% 10% 15% 21% 14% 1	2739
June	1st to 10th	Night	42% 7% 11% 25% 13% 2	1520
	11th to 20th	Night	38% 8% 17% 26% 12%	1520
	21st to end	Night	35% 9% 16% 26% 14% 1	1520
July	1st to 10th	Night	37% 8% 16% 23% 15% 1	2480
	11th to 20th	Night	36% 8% 17% 26% 13%	2472
	21st to end	Night	42% 6% 12% 26% 12% 1	2651
August	1st to 10th	Night	44% 8% 15% 24% 9%	2555
	11th to 20th	Night	41% 7% 16% 27% 9%	3087
	21st to end	Night	31% 7% 12% 38% 12% 1	3476
September	1st to 10th	Night	38% 7% 11% 29% 15% 1	1900
	11th to 20th	Night	31% 5% 14% 26% 23% 1	1972
	21st to end	Night	40% 5% 13% 24% 17% 1	2090
October	1st to 10th	Night	45% 5% 12% 23% 14% 1	3694
	11th to 20th	Night	32% 6% 14% 24% 21% 4	3779
	21st to end	Night	37% 6% 16% 29% 11% 1	4425
November	1st to 10th	Night	42% 5% 12% 22% 16% 2	2453
	11th to 20th	Night	46% 6% 13% 22% 11% 2	2470
	21st to end	Night	45% 6% 18% 23% 8% 1	2626
December	1st to 10th	Night	52% 8% 15% 20% 7%	2660
	11th to 20th	Night	52% 5% 15% 16% 10% 1	3288
	21st to end	Night	60% 7% 11% 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	32% 21% 32% 11% 4 1	180
	11th to 20th	Day	39% 22% 26% 10% 3 1	180
	21st to end	Day	26% 23% 35% 12% 3	238
February	1st to 10th	Day	36% 27% 28% 8% 1	270
	11th to 20th	Day	34% 27% 29% 9% 1	416
	21st to end	Day	32% 21% 34% 12% 1	382
March	1st to 10th	Day	31% 20% 34% 13% 2	460
	11th to 20th	Day	34% 22% 28% 12% 3 1	460
	21st to end	Day	35% 22% 26% 11% 3 2	506
April	1st to 10th	Day	33% 23% 26% 12% 6% 1	460
	11th to 20th	Day	29% 27% 24% 13% 5% 2	452
	21st to end	Day	32% 19% 31% 12% 5% 2	460
May	1st to 10th	Day	31% 19% 28% 14% 5% 3	463
	11th to 20th	Day	20% 18% 31% 21% 7% 2	487
	21st to end	Day	18% 11% 32% 25% 10% 3	529
June	1st to 10th	Day	20% 13% 32% 23% 10% 1	490
	11th to 20th	Day	17% 13% 32% 24% 11% 2	490
	21st to end	Day	17% 16% 30% 25% 10% 2	490
July	1st to 10th	Day	12% 10% 31% 29% 15% 3	485
	11th to 20th	Day	12% 7% 30% 33% 13% 4	484
	21st to end	Day	13% 8% 37% 25% 13% 3	532
August	1st to 10th	Day	12% 8% 29% 30% 16% 5%	486
	11th to 20th	Day	14% 7% 30% 29% 13% 6%	479
	21st to end	Day	14% 11% 28% 27% 14% 7%	539
September	1st to 10th	Day	17% 10% 28% 23% 16% 7%	490
	11th to 20th	Day	15% 9% 27% 22% 17% 11%	490
	21st to end	Day	22% 9% 28% 24% 13% 4	490
October	1st to 10th	Day	26% 12% 26% 19% 14% 4	490
	11th to 20th	Day	23% 17% 28% 24% 8% 2	490
	21st to end	Day	27% 17% 30% 19% 7% 1	444
November	1st to 10th	Day	24% 18% 25% 21% 10% 1	374
	11th to 20th	Day	31% 21% 25% 18% 4 1	370
	21st to end	Day	27% 21% 31% 20% 1	209
December	1st to 10th	Day	30% 25% 26% 14% 4 1	180
	11th to 20th	Day	38% 18% 34% 8% 2	180
	21st to end	Day	31% 21% 33% 12% 3 1	198
January	1st to 10th	Night	26% 23% 32% 17% 3	760
	11th to 20th	Night	28% 19% 32% 18% 3	760
	21st to end	Night	22% 23% 36% 17% 2	836
February	1st to 10th	Night	25% 21% 36% 17% 1	760
	11th to 20th	Night	25% 25% 32% 17%	743
	21st to end	Night	30% 21% 31% 15% 3	628
March	1st to 10th	Night	29% 21% 33% 15% 3	760
	11th to 20th	Night	25% 26% 29% 17% 3	760
	21st to end	Night	28% 22% 30% 16% 4 1	836
April	1st to 10th	Night	27% 22% 31% 17% 3	760
	11th to 20th	Night	26% 19% 31% 18% 6%	751
	21st to end	Night	25% 19% 29% 20% 7%	697
May	1st to 10th	Night	29% 15% 27% 22% 6% 1	527
	11th to 20th	Night	20% 16% 34% 24% 5% 1	374
	21st to end	Night	16% 8% 28% 35% 11% 1	411
June	1st to 10th	Night	19% 10% 31% 26% 13% 1	380
	11th to 20th	Night	18% 10% 27% 32% 12%	380
	21st to end	Night	12% 7% 32% 35% 13% 1	380
July	1st to 10th	Night	12% 8% 22% 39% 18% 1	370
	11th to 20th	Night	14% 7% 22% 38% 17% 2	368
	21st to end	Night	14% 5% 24% 42% 14%	416
August	1st to 10th	Night	12% 4 25% 37% 20% 2	411
	11th to 20th	Night	14% 6% 23% 36% 17% 4	722
	21st to end	Night	15% 7% 22% 35% 19% 2	836
September	1st to 10th	Night	15% 7% 27% 30% 19% 2	760
	11th to 20th	Night	16% 7% 25% 27% 19% 6%	760
	21st to end	Night	17% 9% 26% 33% 13% 2	760
October	1st to 10th	Night	24% 12% 22% 25% 15% 1	760
	11th to 20th	Night	21% 13% 29% 27% 9%	760
	21st to end	Night	27% 18% 27% 22% 6%	836
November	1st to 10th	Night	22% 17% 28% 25% 8% 1	755
	11th to 20th	Night	25% 18% 29% 21% 6% 2	760
	21st to end	Night	24% 20% 28% 23% 5% 1	760
December	1st to 10th	Night	24% 23% 32% 16% 4	760
	11th to 20th	Night	28% 18% 32% 19% 3	760
	21st to end	Night	31% 24% 26% 17% 2	836

Page generated at 2024-11-01 22:47:30. Version ac07

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