Rutland
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rutland clear sky chart from 2005-11-06 to 2024-11-03.

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	18% 11% 4 8% 5% 4 4 4 5% 7% 30%	101372
	Night	18% 13% 4 9% 5% 4 4 3 5% 5% 29%	97638
Transparency	Day	53% 7% 11% 19% 9% 1	101130
	Night	55% 6% 11% 17% 9% 1	97500
Seeing	Day	27% 20% 28% 16% 7% 2	14791
	Night	25% 19% 25% 22% 8% 1	23747

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	15% 18% 7% 10% 5% 4 5% 3 4 4 25%	2517
	11th to 20th	Day	14% 16% 6% 15% 10% 5% 3 3 3 5% 20%	2520
	21st to end	Day	17% 20% 8% 11% 6% 4 4 3 3 5% 19%	2772
February	1st to 10th	Day	14% 16% 4 10% 7% 6% 4 4 5% 6% 23%	1691
	11th to 20th	Day	12% 16% 5% 15% 7% 4 4 5% 4 5% 23%	1844
	21st to end	Day	16% 14% 6% 12% 7% 4 3 3 4 6% 25%	1570
March	1st to 10th	Day	23% 16% 5% 9% 5% 5% 4 4 4 4 22%	3116
	11th to 20th	Day	15% 21% 6% 9% 5% 3 4 3 4 5% 24%	3264
	21st to end	Day	19% 11% 4 11% 5% 5% 4 3 3 4 31%	4166
April	1st to 10th	Day	21% 16% 3 7% 3 3 3 3 5% 5% 30%	2280
	11th to 20th	Day	18% 13% 3 7% 5% 4 4 3 4 6% 33%	2254
	21st to end	Day	23% 13% 4 8% 4 3 3 3 5% 6% 30%	2427
May	1st to 10th	Day	27% 10% 3 7% 4 4 5% 3 5% 6% 26%	4158
	11th to 20th	Day	18% 9% 3 7% 5% 5% 5% 4 6% 7% 30%	4398
	21st to end	Day	14% 7% 3 6% 4 4 5% 4 6% 8% 38%	4837
June	1st to 10th	Day	21% 8% 3 8% 5% 6% 6% 4 6% 7% 27%	2660
	11th to 20th	Day	20% 7% 2 6% 5% 4 5% 4 6% 8% 32%	2660
	21st to end	Day	21% 10% 3 7% 5% 5% 5% 4 6% 6% 28%	2660
July	1st to 10th	Day	14% 7% 2 6% 5% 4 6% 4 7% 11% 34%	4440
	11th to 20th	Day	13% 6% 3 7% 6% 5% 5% 5% 8% 9% 33%	4440
	21st to end	Day	16% 6% 3 7% 5% 5% 5% 5% 6% 8% 36%	4814
August	1st to 10th	Day	16% 8% 3 7% 5% 5% 6% 4 7% 8% 31%	4377
	11th to 20th	Day	16% 8% 2 7% 5% 6% 5% 5% 6% 8% 32%	3863
	21st to end	Day	15% 6% 2 5% 4 4 5% 4 7% 9% 39%	4180
September	1st to 10th	Day	16% 6% 2 6% 4 4 5% 4 6% 7% 42%	2280
	11th to 20th	Day	16% 6% 2 5% 3 3 4 3 4 7% 48%	2161
	21st to end	Day	17% 7% 2 6% 3 5% 4 4 6% 7% 40%	2090
October	1st to 10th	Day	23% 9% 3 7% 4 4 4 4 4 5% 32%	2028
	11th to 20th	Day	17% 11% 3 7% 4 5% 4 3 4 8% 34%	1854
	21st to end	Day	25% 13% 3 7% 4 4 4 3 4 5% 28%	1881
November	1st to 10th	Day	16% 12% 4 7% 4 3 4 4 5% 5% 36%	1689
	11th to 20th	Day	18% 14% 4 9% 4 4 4 4 5% 5% 30%	1710
	21st to end	Day	18% 13% 5% 9% 4 5% 4 4 4 6% 27%	1573
December	1st to 10th	Day	20% 19% 4 11% 5% 3 4 3 5% 6% 20%	1520
	11th to 20th	Day	20% 16% 6% 9% 4 4 4 2 4 5% 25%	1906
	21st to end	Day	22% 19% 6% 11% 5% 4 4 2 3 4 20%	2772
January	1st to 10th	Night	14% 16% 7% 13% 5% 4 4 3 4 4 26%	4429
	11th to 20th	Night	12% 19% 7% 17% 10% 5% 4 3 4 4 16%	4440
	21st to end	Night	21% 18% 7% 13% 6% 5% 3 2 3 3 19%	4884
February	1st to 10th	Night	15% 15% 6% 13% 8% 5% 4 3 5% 5% 20%	2487
	11th to 20th	Night	12% 12% 6% 12% 8% 7% 6% 5% 6% 4 23%	2220
	21st to end	Night	14% 15% 4 12% 6% 5% 4 3 5% 4 29%	1884
March	1st to 10th	Night	22% 12% 4 8% 6% 4 4 3 6% 5% 26%	3724
	11th to 20th	Night	14% 21% 4 8% 5% 4 4 3 4 5% 28%	3691
	21st to end	Night	20% 16% 4 10% 4 3 3 2 3 3 31%	3466
April	1st to 10th	Night	21% 13% 4 8% 5% 3 4 3 5% 6% 29%	1900
	11th to 20th	Night	20% 14% 4 6% 5% 4 4 3 4 6% 31%	1875
	21st to end	Night	21% 13% 5% 6% 4 3 3 2 5% 4 32%	1753
May	1st to 10th	Night	28% 11% 3 7% 5% 4 4 3 5% 5% 25%	2812
	11th to 20th	Night	20% 11% 3 9% 6% 5% 4 3 5% 5% 29%	2495
	21st to end	Night	17% 7% 3 5% 4 4 5% 4 7% 8% 36%	2738
June	1st to 10th	Night	21% 8% 2 7% 5% 4 5% 5% 6% 7% 32%	1520
	11th to 20th	Night	22% 7% 2 5% 4 4 4 4 5% 7% 37%	1520
	21st to end	Night	20% 8% 3 6% 4 4 5% 3 6% 7% 34%	1520
July	1st to 10th	Night	15% 7% 2 8% 6% 6% 6% 5% 5% 7% 33%	2520
	11th to 20th	Night	19% 9% 2 6% 4 4 5% 4 7% 7% 34%	2520
	21st to end	Night	16% 8% 2 7% 5% 4 5% 4 5% 6% 38%	2739
August	1st to 10th	Night	25% 10% 3 6% 5% 4 3 2 4 6% 34%	2520
	11th to 20th	Night	16% 7% 3 8% 5% 3 4 4 6% 8% 37%	2962
	21st to end	Night	13% 8% 2 5% 3 4 4 4 6% 9% 42%	3476
September	1st to 10th	Night	16% 8% 2 5% 3 4 4 4 4 6% 44%	1900
	11th to 20th	Night	16% 5% 2 4 3 3 3 3 4 5% 51%	2019
	21st to end	Night	17% 7% 2 5% 4 4 3 3 5% 6% 44%	2090
October	1st to 10th	Night	23% 9% 3 7% 4 4 3 3 5% 6% 33%	2150
	11th to 20th	Night	18% 11% 3 8% 5% 4 4 4 5% 6% 33%	2325
	21st to end	Night	23% 14% 3 7% 5% 5% 4 3 5% 5% 26%	2717
November	1st to 10th	Night	18% 12% 4 8% 5% 5% 3 3 4 4 33%	2434
	11th to 20th	Night	18% 14% 4 7% 4 3 4 3 5% 6% 31%	2470
	21st to end	Night	17% 14% 4 10% 5% 3 4 4 4 6% 28%	2606
December	1st to 10th	Night	20% 21% 6% 11% 6% 4 4 3 4 4 17%	2660
	11th to 20th	Night	20% 16% 5% 9% 5% 4 4 4 5% 6% 24%	3288
	21st to end	Night	23% 17% 6% 12% 5% 3 3 3 4 4 19%	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	62% 5% 9% 19% 5%	2518
	11th to 20th	Day	67% 7% 8% 13% 4 1	2520
	21st to end	Day	68% 6% 9% 11% 5% 1	2772
February	1st to 10th	Day	61% 7% 10% 14% 7% 1	1691
	11th to 20th	Day	62% 6% 8% 15% 8% 1	1853
	21st to end	Day	62% 4 10% 13% 10% 1	1570
March	1st to 10th	Day	64% 8% 8% 9% 9% 1	3119
	11th to 20th	Day	61% 6% 11% 12% 8% 1	3264
	21st to end	Day	57% 5% 6% 13% 17% 2	4166
April	1st to 10th	Day	56% 4 8% 19% 10% 2	2280
	11th to 20th	Day	52% 6% 9% 19% 13% 1	2254
	21st to end	Day	56% 6% 8% 16% 11% 2	2427
May	1st to 10th	Day	59% 7% 9% 17% 7% 1	4172
	11th to 20th	Day	51% 9% 14% 17% 8% 1	4402
	21st to end	Day	41% 8% 12% 27% 11% 1	4837
June	1st to 10th	Day	54% 8% 12% 17% 8%	2660
	11th to 20th	Day	49% 7% 11% 20% 12% 1	2660
	21st to end	Day	55% 8% 10% 17% 8% 1	2660
July	1st to 10th	Day	43% 7% 14% 25% 11%	4370
	11th to 20th	Day	43% 9% 15% 25% 7%	4365
	21st to end	Day	45% 8% 14% 24% 9%	4661
August	1st to 10th	Day	50% 8% 14% 19% 9%	4363
	11th to 20th	Day	48% 8% 16% 23% 5%	3902
	21st to end	Day	39% 7% 17% 25% 11% 1	4180
September	1st to 10th	Day	40% 7% 12% 28% 12%	2280
	11th to 20th	Day	37% 6% 9% 30% 17% 1	2161
	21st to end	Day	43% 7% 12% 25% 11% 2	2090
October	1st to 10th	Day	54% 5% 9% 18% 12% 1	2028
	11th to 20th	Day	49% 6% 13% 22% 8% 1	1854
	21st to end	Day	59% 5% 10% 16% 8% 1	1881
November	1st to 10th	Day	49% 7% 12% 20% 12%	1689
	11th to 20th	Day	55% 6% 10% 15% 12% 2	1710
	21st to end	Day	59% 6% 14% 15% 5% 1	1573
December	1st to 10th	Day	65% 8% 11% 10% 5% 1	1520
	11th to 20th	Day	63% 4 9% 15% 7% 1	1906
	21st to end	Day	68% 6% 7% 12% 7%	2772
January	1st to 10th	Night	61% 5% 12% 14% 6%	4429
	11th to 20th	Night	69% 7% 9% 9% 5% 1	4440
	21st to end	Night	70% 5% 7% 11% 6% 1	4884
February	1st to 10th	Night	64% 6% 10% 12% 7% 1	2487
	11th to 20th	Night	61% 7% 8% 14% 10% 1	2222
	21st to end	Night	59% 4 12% 16% 7% 2	1884
March	1st to 10th	Night	59% 7% 8% 16% 8% 2	3734
	11th to 20th	Night	57% 6% 12% 15% 9% 1	3692
	21st to end	Night	59% 3 6% 13% 17% 3	3466
April	1st to 10th	Night	56% 5% 9% 18% 10% 1	1900
	11th to 20th	Night	53% 6% 9% 19% 12% 1	1875
	21st to end	Night	54% 6% 8% 18% 11% 3	1753
May	1st to 10th	Night	58% 7% 9% 16% 8% 1	2818
	11th to 20th	Night	55% 8% 12% 17% 7% 1	2496
	21st to end	Night	42% 9% 15% 20% 12% 1	2739
June	1st to 10th	Night	50% 8% 12% 18% 11% 1	1520
	11th to 20th	Night	48% 6% 14% 19% 11% 1	1520
	21st to end	Night	49% 7% 13% 22% 8% 1	1520
July	1st to 10th	Night	48% 8% 14% 18% 11% 1	2480
	11th to 20th	Night	46% 7% 13% 25% 8%	2472
	21st to end	Night	45% 6% 12% 26% 10% 1	2651
August	1st to 10th	Night	53% 6% 12% 19% 9%	2510
	11th to 20th	Night	44% 7% 18% 22% 8%	2989
	21st to end	Night	37% 7% 18% 26% 11% 1	3476
September	1st to 10th	Night	39% 7% 13% 28% 12%	1900
	11th to 20th	Night	35% 6% 11% 30% 17% 1	2019
	21st to end	Night	42% 5% 12% 24% 14% 2	2090
October	1st to 10th	Night	51% 7% 9% 21% 9% 2	2150
	11th to 20th	Night	51% 7% 12% 21% 9% 1	2325
	21st to end	Night	60% 6% 9% 16% 8% 1	2717
November	1st to 10th	Night	54% 6% 10% 17% 11% 2	2434
	11th to 20th	Night	54% 6% 10% 17% 10% 3	2470
	21st to end	Night	56% 6% 13% 17% 7%	2606
December	1st to 10th	Night	69% 6% 9% 12% 3	2660
	11th to 20th	Night	62% 6% 10% 11% 10%	3288
	21st to end	Night	68% 6% 8% 12% 6%	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	34% 28% 24% 12% 2	180
	11th to 20th	Day	35% 23% 31% 9% 2 1	180
	21st to end	Day	22% 30% 35% 10% 3	198
February	1st to 10th	Day	34% 41% 20% 4 1	261
	11th to 20th	Day	31% 31% 26% 10% 2	452
	21st to end	Day	35% 26% 25% 11% 2	382
March	1st to 10th	Day	33% 24% 29% 11% 2	460
	11th to 20th	Day	32% 26% 27% 12% 3 1	460
	21st to end	Day	33% 27% 23% 11% 5% 2	506
April	1st to 10th	Day	40% 19% 25% 11% 5% 1	460
	11th to 20th	Day	37% 25% 20% 12% 4 2	452
	21st to end	Day	35% 23% 27% 10% 4 2	460
May	1st to 10th	Day	36% 22% 24% 12% 5% 2	463
	11th to 20th	Day	23% 19% 35% 17% 4 2	487
	21st to end	Day	20% 19% 35% 19% 6% 2	529
June	1st to 10th	Day	26% 20% 32% 15% 5% 1	490
	11th to 20th	Day	25% 15% 32% 19% 8%	490
	21st to end	Day	26% 19% 31% 19% 4 1	490
July	1st to 10th	Day	21% 14% 32% 22% 9% 2	485
	11th to 20th	Day	14% 13% 40% 24% 8% 1	484
	21st to end	Day	17% 13% 40% 23% 6% 2	532
August	1st to 10th	Day	18% 14% 29% 26% 11% 3	486
	11th to 20th	Day	20% 14% 28% 21% 11% 6%	479
	21st to end	Day	19% 14% 27% 23% 12% 5%	539
September	1st to 10th	Day	18% 15% 29% 21% 11% 6%	490
	11th to 20th	Day	19% 15% 22% 18% 18% 8%	490
	21st to end	Day	20% 15% 29% 19% 11% 5%	490
October	1st to 10th	Day	29% 13% 27% 18% 11% 2	490
	11th to 20th	Day	28% 18% 26% 19% 9%	465
	21st to end	Day	35% 21% 24% 15% 4	429
November	1st to 10th	Day	28% 22% 24% 16% 8% 1	371
	11th to 20th	Day	30% 27% 24% 12% 6% 1	370
	21st to end	Day	30% 27% 31% 9% 2 1	233
December	1st to 10th	Day	32% 34% 24% 8% 2 1	180
	11th to 20th	Day	39% 31% 22% 7% 2	180
	21st to end	Day	36% 27% 24% 9% 4 1	198
January	1st to 10th	Night	25% 29% 30% 14% 3	760
	11th to 20th	Night	30% 24% 26% 17% 2 1	760
	21st to end	Night	20% 27% 30% 19% 4	836
February	1st to 10th	Night	24% 28% 33% 13% 2	760
	11th to 20th	Night	23% 31% 27% 17% 2	743
	21st to end	Night	26% 26% 30% 16% 2	628
March	1st to 10th	Night	25% 25% 30% 17% 3	760
	11th to 20th	Night	30% 23% 26% 16% 5%	760
	21st to end	Night	30% 21% 25% 17% 7%	836
April	1st to 10th	Night	30% 21% 25% 20% 4	760
	11th to 20th	Night	28% 24% 24% 16% 8%	751
	21st to end	Night	31% 19% 23% 21% 6% 1	613
May	1st to 10th	Night	32% 15% 27% 19% 8%	561
	11th to 20th	Night	21% 17% 27% 29% 6% 1	374
	21st to end	Night	20% 11% 26% 31% 11% 1	411
June	1st to 10th	Night	23% 9% 29% 27% 12% 1	380
	11th to 20th	Night	24% 9% 21% 33% 13% 1	380
	21st to end	Night	22% 8% 25% 32% 12% 1	380
July	1st to 10th	Night	18% 5% 21% 41% 13% 2	370
	11th to 20th	Night	18% 3 23% 37% 17% 1	368
	21st to end	Night	16% 4 28% 35% 17%	416
August	1st to 10th	Night	19% 5% 16% 38% 21% 1	379
	11th to 20th	Night	19% 6% 21% 33% 17% 3	664
	21st to end	Night	20% 6% 20% 32% 21% 2	836
September	1st to 10th	Night	20% 9% 22% 30% 17% 2	760
	11th to 20th	Night	20% 9% 19% 26% 22% 5%	760
	21st to end	Night	22% 11% 23% 26% 15% 3	760
October	1st to 10th	Night	29% 12% 18% 24% 13% 2	760
	11th to 20th	Night	25% 16% 24% 23% 11% 1	760
	21st to end	Night	31% 20% 24% 18% 6%	836
November	1st to 10th	Night	26% 20% 27% 19% 8% 1	749
	11th to 20th	Night	26% 23% 25% 18% 7% 1	760
	21st to end	Night	28% 27% 23% 16% 5% 1	760
December	1st to 10th	Night	33% 26% 23% 14% 3	760
	11th to 20th	Night	29% 28% 22% 17% 4	760
	21st to end	Night	31% 26% 27% 14% 2	836

Page generated at 2024-10-31 03:39:27. Version ac07

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