Torrington
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Torrington clear sky chart from 2005-11-06 to 2025-04-26.

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	6% 5% 2 5% 3 4 4 4 6% 8% 54%	117515
	Night	6% 6% 2 6% 4 4 4 4 5% 7% 52%	119961
Transparency	Day	28% 5% 12% 26% 21% 8%	117256
	Night	30% 5% 13% 27% 19% 5%	119810
Seeing	Day	9% 8% 26% 31% 20% 6%	16338
	Night	9% 7% 34% 39% 10%	26485

By Month

Percentage Cloud Cover SW (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	3 8% 4 9% 5% 4 4 3 5% 6% 49%	3638
	11th to 20th	Day	2 11% 3 8% 5% 5% 6% 4 6% 6% 43%	3640
	21st to end	Day	2 4 2 5% 4 4 4 3 5% 6% 63%	4257
February	1st to 10th	Day	5% 9% 4 8% 5% 4 5% 4 5% 6% 47%	1800
	11th to 20th	Day	5% 9% 3 7% 4 4 5% 4 5% 7% 46%	1918
	21st to end	Day	5% 8% 3 6% 4 3 3 3 5% 7% 54%	1650
March	1st to 10th	Day	9% 8% 3 6% 3 3 3 3 5% 7% 51%	4500
	11th to 20th	Day	6% 6% 2 5% 4 3 4 3 5% 7% 56%	4761
	21st to end	Day	9% 6% 2 6% 4 4 4 4 6% 9% 45%	5920
April	1st to 10th	Day	9% 7% 3 6% 4 3 4 4 6% 7% 48%	2400
	11th to 20th	Day	13% 7% 2 6% 4 4 4 4 6% 8% 41%	2371
	21st to end	Day	11% 8% 2 5% 4 4 3 4 6% 8% 46%	2391
May	1st to 10th	Day	14% 7% 2 6% 5% 5% 4 3 5% 7% 42%	4170
	11th to 20th	Day	11% 4 1 4 3 5% 5% 4 6% 9% 47%	4388
	21st to end	Day	10% 5% 1 6% 4 4 5% 4 6% 8% 46%	4825
June	1st to 10th	Day	6% 3 1 4 4 5% 5% 4 7% 9% 53%	2660
	11th to 20th	Day	8% 4 1 5% 3 4 4 4 6% 9% 52%	2660
	21st to end	Day	5% 2 1 3 3 4 4 4 6% 9% 59%	2660
July	1st to 10th	Day	5% 3 1 3 3 3 4 3 5% 8% 62%	4430
	11th to 20th	Day	3 1 1 3 2 3 4 5% 7% 10% 61%	4430
	21st to end	Day	3 2 1 4 3 3 4 4 7% 9% 59%	4802
August	1st to 10th	Day	9% 3 1 3 3 3 4 3 7% 10% 53%	4298
	11th to 20th	Day	3 3 1 4 4 4 5% 4 7% 8% 57%	3741
	21st to end	Day	4 3 1 5% 3 3 4 4 5% 8% 60%	4180
September	1st to 10th	Day	6% 4 1 3 3 2 3 3 5% 7% 63%	2280
	11th to 20th	Day	7% 2 1 4 3 2 3 3 5% 7% 64%	2224
	21st to end	Day	7% 4 1 3 2 2 3 2 5% 8% 64%	2090
October	1st to 10th	Day	6% 3 1 2 2 1 2 2 3 3 75%	3268
	11th to 20th	Day	9% 4 1 4 3 3 4 2 5% 6% 59%	3150
	21st to end	Day	8% 5% 2 4 3 3 3 3 5% 7% 57%	3154
November	1st to 10th	Day	4 6% 2 4 3 4 4 3 6% 8% 56%	1763
	11th to 20th	Day	4 4 2 4 3 4 3 3 5% 9% 59%	1800
	21st to end	Day	5% 7% 2 5% 3 3 3 4 6% 6% 57%	1646
December	1st to 10th	Day	3 4 2 4 2 3 4 3 5% 6% 64%	2620
	11th to 20th	Day	3 5% 1 3 3 3 3 4 5% 9% 60%	3026
	21st to end	Day	5% 8% 3 6% 4 4 5% 3 6% 8% 47%	4004
January	1st to 10th	Night	4 9% 3 8% 5% 4 5% 4 6% 7% 45%	6327
	11th to 20th	Night	3 7% 4 8% 5% 5% 5% 4 6% 7% 46%	6340
	21st to end	Night	3 5% 2 8% 5% 4 5% 3 4 6% 56%	6762
February	1st to 10th	Night	4 10% 3 7% 5% 4 5% 4 6% 7% 45%	2600
	11th to 20th	Night	6% 9% 4 8% 5% 4 5% 3 6% 7% 44%	2368
	21st to end	Night	4 8% 3 7% 4 3 4 4 6% 6% 51%	1980
March	1st to 10th	Night	8% 11% 3 5% 3 3 3 3 4 5% 54%	5374
	11th to 20th	Night	5% 6% 2 6% 3 3 4 3 5% 6% 56%	5225
	21st to end	Night	11% 9% 3 7% 4 4 5% 4 6% 8% 40%	5034
April	1st to 10th	Night	11% 6% 3 5% 4 3 4 3 5% 6% 50%	2000
	11th to 20th	Night	11% 7% 2 5% 4 4 4 3 6% 7% 47%	1977
	21st to end	Night	16% 6% 2 6% 4 4 4 5% 5% 5% 43%	1903
May	1st to 10th	Night	14% 9% 3 6% 4 4 4 3 4 7% 41%	2798
	11th to 20th	Night	11% 4 1 5% 3 3 4 4 7% 10% 50%	2517
	21st to end	Night	13% 4 1 5% 3 3 4 4 6% 9% 48%	2762
June	1st to 10th	Night	6% 4 1 5% 4 4 4 5% 7% 9% 51%	1520
	11th to 20th	Night	8% 3 2 4 3 4 4 3 6% 9% 54%	1520
	21st to end	Night	5% 2 1 3 3 4 4 4 7% 10% 57%	1520
July	1st to 10th	Night	6% 3 2 5% 5% 5% 4 4 6% 6% 54%	2540
	11th to 20th	Night	3 2 1 4 3 4 5% 4 7% 10% 58%	2540
	21st to end	Night	3 3 1 6% 4 4 5% 4 6% 10% 53%	2761
August	1st to 10th	Night	12% 4 2 5% 4 4 5% 4 7% 9% 45%	2623
	11th to 20th	Night	3 2 2 5% 4 5% 6% 5% 7% 9% 52%	3084
	21st to end	Night	4 3 1 5% 4 4 5% 4 7% 8% 55%	3487
September	1st to 10th	Night	8% 4 2 4 3 2 3 3 5% 7% 60%	1900
	11th to 20th	Night	7% 4 1 4 3 3 3 3 3 7% 63%	1955
	21st to end	Night	8% 4 1 4 3 3 3 3 4 4 62%	2090
October	1st to 10th	Night	7% 2 1 2 2 2 2 2 2 4 74%	3694
	11th to 20th	Night	9% 3 1 4 3 3 4 3 5% 6% 59%	3778
	21st to end	Night	8% 5% 1 4 3 3 3 3 6% 7% 57%	4372
November	1st to 10th	Night	7% 6% 2 5% 3 3 3 3 6% 8% 55%	2535
	11th to 20th	Night	4 5% 2 4 4 4 4 4 6% 6% 56%	2600
	21st to end	Night	5% 7% 2 5% 3 3 3 3 5% 7% 57%	2750
December	1st to 10th	Night	3 4 2 5% 4 3 3 2 4 6% 64%	4570
	11th to 20th	Night	3 6% 2 5% 4 4 4 4 6% 8% 54%	5181
	21st to end	Night	6% 9% 3 7% 4 4 5% 4 5% 7% 45%	6974

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	36% 4 13% 29% 18%	3639
	11th to 20th	Day	39% 6% 14% 22% 17% 3	3640
	21st to end	Day	23% 4 17% 28% 24% 5%	4257
February	1st to 10th	Day	37% 5% 16% 23% 16% 3	1800
	11th to 20th	Day	36% 7% 12% 25% 16% 4	1928
	21st to end	Day	32% 3 13% 28% 18% 6%	1650
March	1st to 10th	Day	33% 4 6% 28% 25% 4	4500
	11th to 20th	Day	28% 4 13% 30% 23% 2	4761
	21st to end	Day	34% 7% 15% 30% 13% 1	5920
April	1st to 10th	Day	34% 6% 14% 26% 15% 5%	2400
	11th to 20th	Day	38% 6% 12% 21% 19% 4	2374
	21st to end	Day	36% 5% 12% 28% 17% 2	2391
May	1st to 10th	Day	40% 6% 12% 24% 13% 5%	4170
	11th to 20th	Day	31% 7% 14% 30% 16% 3	4392
	21st to end	Day	32% 7% 16% 28% 15% 3	4825
June	1st to 10th	Day	25% 8% 18% 27% 17% 5%	2660
	11th to 20th	Day	28% 6% 13% 24% 21% 9%	2660
	21st to end	Day	20% 6% 10% 26% 27% 12%	2660
July	1st to 10th	Day	21% 5% 8% 21% 27% 19%	4361
	11th to 20th	Day	16% 6% 10% 27% 26% 15%	4355
	21st to end	Day	19% 5% 9% 21% 24% 22%	4651
August	1st to 10th	Day	25% 5% 14% 26% 22% 9%	4283
	11th to 20th	Day	24% 6% 10% 22% 24% 15%	3777
	21st to end	Day	22% 5% 9% 18% 26% 20%	4179
September	1st to 10th	Day	21% 4 7% 20% 30% 18%	2280
	11th to 20th	Day	20% 4 8% 24% 28% 16%	2224
	21st to end	Day	21% 4 7% 26% 33% 9%	2090
October	1st to 10th	Day	16% 3 7% 17% 31% 25%	3268
	11th to 20th	Day	27% 4 10% 29% 23% 6%	3150
	21st to end	Day	27% 3 12% 31% 23% 4	3154
November	1st to 10th	Day	25% 4 15% 27% 22% 7%	1763
	11th to 20th	Day	23% 4 12% 31% 26% 4	1800
	21st to end	Day	26% 4 12% 28% 26% 4	1646
December	1st to 10th	Day	21% 4 14% 34% 25% 2	2620
	11th to 20th	Day	21% 4 15% 39% 18% 2	3024
	21st to end	Day	34% 4 11% 34% 14% 1	4004
January	1st to 10th	Night	36% 5% 13% 30% 13% 2	6327
	11th to 20th	Night	35% 6% 16% 21% 19% 2	6340
	21st to end	Night	30% 4 16% 31% 18% 3	6762
February	1st to 10th	Night	37% 6% 16% 26% 13% 2	2600
	11th to 20th	Night	39% 6% 13% 24% 15% 3	2368
	21st to end	Night	32% 6% 12% 28% 18% 4	1980
March	1st to 10th	Night	34% 4 6% 27% 25% 4	5374
	11th to 20th	Night	28% 4 12% 25% 28% 2	5225
	21st to end	Night	40% 5% 21% 21% 12% 1	5034
April	1st to 10th	Night	34% 7% 13% 26% 16% 5%	2000
	11th to 20th	Night	35% 6% 13% 25% 17% 4	1977
	21st to end	Night	42% 6% 9% 28% 15% 1	1903
May	1st to 10th	Night	42% 7% 11% 22% 16% 2	2798
	11th to 20th	Night	28% 8% 18% 32% 10% 4	2518
	21st to end	Night	32% 7% 19% 27% 11% 3	2762
June	1st to 10th	Night	28% 8% 24% 23% 13% 4	1520
	11th to 20th	Night	27% 7% 16% 26% 18% 7%	1520
	21st to end	Night	21% 6% 15% 27% 22% 8%	1520
July	1st to 10th	Night	27% 6% 10% 24% 21% 12%	2500
	11th to 20th	Night	19% 6% 18% 26% 22% 9%	2492
	21st to end	Night	25% 6% 14% 23% 21% 11%	2674
August	1st to 10th	Night	35% 6% 15% 21% 17% 5%	2615
	11th to 20th	Night	26% 9% 14% 23% 19% 9%	3114
	21st to end	Night	25% 7% 11% 20% 24% 13%	3487
September	1st to 10th	Night	25% 5% 7% 24% 25% 15%	1900
	11th to 20th	Night	23% 5% 8% 26% 25% 12%	1955
	21st to end	Night	25% 5% 7% 26% 26% 12%	2090
October	1st to 10th	Night	17% 3 7% 17% 32% 24%	3694
	11th to 20th	Night	26% 4 13% 29% 21% 7%	3778
	21st to end	Night	27% 4 11% 29% 21% 9%	4372
November	1st to 10th	Night	27% 4 13% 26% 24% 5%	2535
	11th to 20th	Night	27% 5% 10% 30% 22% 6%	2600
	21st to end	Night	28% 4 10% 31% 22% 5%	2750
December	1st to 10th	Night	24% 4 14% 35% 21% 3	4570
	11th to 20th	Night	27% 5% 12% 40% 16% 1	5182
	21st to end	Night	37% 5% 11% 33% 13% 1	6974

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	9% 6% 30% 33% 17% 5%	300
	11th to 20th	Day	10% 13% 39% 25% 12% 1	300
	21st to end	Day	6% 9% 46% 29% 7% 3	330
February	1st to 10th	Day	12% 13% 45% 25% 6%	300
	11th to 20th	Day	9% 13% 44% 25% 8% 1	300
	21st to end	Day	10% 19% 34% 31% 6% 1	249
March	1st to 10th	Day	10% 12% 29% 34% 14% 1	300
	11th to 20th	Day	12% 14% 31% 28% 12% 3	391
	21st to end	Day	15% 14% 33% 25% 9% 3	550
April	1st to 10th	Day	14% 16% 34% 24% 10% 2	500
	11th to 20th	Day	15% 21% 30% 23% 10% 2	492
	21st to end	Day	14% 12% 27% 29% 15% 3	531
May	1st to 10th	Day	17% 11% 27% 27% 15% 3	653
	11th to 20th	Day	18% 7% 21% 28% 20% 6%	675
	21st to end	Day	14% 8% 24% 29% 21% 5%	734
June	1st to 10th	Day	6% 4 21% 36% 26% 8%	680
	11th to 20th	Day	9% 7% 29% 33% 18% 4	680
	21st to end	Day	6% 3 22% 37% 27% 5%	680
July	1st to 10th	Day	5% 4 17% 36% 31% 8%	671
	11th to 20th	Day	6% 3 17% 36% 31% 8%	668
	21st to end	Day	5% 2 14% 33% 39% 7%	739
August	1st to 10th	Day	6% 1 18% 37% 31% 7%	615
	11th to 20th	Day	3 3 23% 32% 26% 13%	477
	21st to end	Day	4 3 23% 31% 27% 12%	539
September	1st to 10th	Day	7% 5% 18% 33% 24% 13%	490
	11th to 20th	Day	6% 4 23% 25% 29% 13%	434
	21st to end	Day	7% 6% 21% 32% 20% 14%	300
October	1st to 10th	Day	12% 5% 22% 24% 22% 15%	300
	11th to 20th	Day	10% 8% 28% 28% 18% 8%	300
	21st to end	Day	10% 11% 32% 30% 13% 5%	330
November	1st to 10th	Day	9% 7% 31% 34% 14% 6%	300
	11th to 20th	Day	6% 10% 34% 34% 14% 2	300
	21st to end	Day	8% 9% 31% 36% 12% 4	300
December	1st to 10th	Day	6% 18% 30% 31% 13% 2	300
	11th to 20th	Day	10% 12% 39% 31% 8% 1	300
	21st to end	Day	12% 16% 29% 27% 14% 2	330
January	1st to 10th	Night	7% 10% 36% 36% 10% 1	1000
	11th to 20th	Night	7% 13% 42% 31% 6% 1	1000
	21st to end	Night	9% 7% 43% 34% 7%	1005
February	1st to 10th	Night	9% 9% 47% 30% 5% 1	800
	11th to 20th	Night	11% 7% 43% 34% 5%	784
	21st to end	Night	8% 13% 45% 29% 5%	660
March	1st to 10th	Night	9% 9% 41% 34% 6%	800
	11th to 20th	Night	9% 8% 33% 43% 6%	800
	21st to end	Night	13% 10% 36% 35% 4 1	684
April	1st to 10th	Night	12% 12% 37% 34% 5%	600
	11th to 20th	Night	14% 9% 39% 34% 5%	593
	21st to end	Night	18% 8% 30% 35% 10%	587
May	1st to 10th	Night	18% 8% 26% 35% 12%	570
	11th to 20th	Night	17% 5% 24% 42% 12% 1	561
	21st to end	Night	13% 6% 29% 38% 14%	617
June	1st to 10th	Night	8% 4 29% 40% 18% 1	570
	11th to 20th	Night	9% 4 37% 43% 7%	570
	21st to end	Night	5% 3 30% 49% 13%	570
July	1st to 10th	Night	6% 3 21% 50% 20% 1	555
	11th to 20th	Night	4 1 21% 56% 17% 1	552
	21st to end	Night	4 2 16% 54% 24% 1	624
August	1st to 10th	Night	7% 2 20% 51% 21%	567
	11th to 20th	Night	4 2 21% 53% 20%	564
	21st to end	Night	4 3 21% 50% 22%	627
September	1st to 10th	Night	8% 4 21% 49% 17% 1	570
	11th to 20th	Night	7% 3 22% 45% 21% 1	570
	21st to end	Night	10% 2 30% 45% 13%	570
October	1st to 10th	Night	14% 4 28% 37% 16% 1	693
	11th to 20th	Night	11% 4 29% 44% 11%	760
	21st to end	Night	10% 6% 34% 38% 11% 1	987
November	1st to 10th	Night	9% 5% 33% 42% 10% 1	975
	11th to 20th	Night	5% 10% 40% 37% 7% 1	1000
	21st to end	Night	8% 8% 34% 43% 7%	1000
December	1st to 10th	Night	8% 9% 45% 34% 6%	1000
	11th to 20th	Night	8% 8% 41% 37% 6%	1000
	21st to end	Night	10% 11% 41% 32% 6%	1100

Page generated at 2025-04-23 07:25:05. Version ac07

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