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 2026-08-30.

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%	152970
	Night	6% 6% 2 6% 4 4 4 4 5% 7% 52%	146775
Transparency	Day	27% 5% 12% 27% 21% 8%	147820
	Night	31% 5% 13% 27% 19% 5%	142937
Seeing	Day	9% 9% 27% 30% 19% 5%	18327
	Night	9% 7% 34% 39% 10%	28220

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	2 7% 4 9% 5% 4 4 3 4 6% 52%	4720
	11th to 20th	Day	2 8% 3 7% 5% 5% 5% 4 6% 7% 47%	4740
	21st to end	Day	2 5% 2 6% 4 4 4 3 5% 7% 58%	5523
February	1st to 10th	Day	5% 9% 4 8% 5% 4 4 4 6% 6% 47%	1890
	11th to 20th	Day	5% 9% 3 7% 4 4 5% 4 6% 7% 45%	2017
	21st to end	Day	5% 8% 3 6% 4 3 3 3 5% 7% 55%	1730
March	1st to 10th	Day	9% 8% 3 6% 3 3 3 3 5% 7% 51%	4600
	11th to 20th	Day	6% 6% 2 5% 4 3 4 3 5% 7% 56%	4866
	21st to end	Day	9% 6% 2 6% 4 4 4 4 6% 9% 45%	6051
April	1st to 10th	Day	8% 7% 3 5% 4 3 4 4 6% 7% 48%	2520
	11th to 20th	Day	13% 7% 2 6% 4 4 4 4 6% 8% 42%	2491
	21st to end	Day	10% 8% 2 5% 4 4 4 4 6% 8% 45%	2576
May	1st to 10th	Day	11% 5% 2 5% 4 4 4 3 5% 6% 50%	7743
	11th to 20th	Day	10% 4 1 5% 3 4 5% 4 6% 9% 48%	8191
	21st to end	Day	12% 4 2 6% 4 4 4 4 6% 8% 47%	9026
June	1st to 10th	Day	6% 3 1 4 4 5% 5% 4 7% 9% 52%	2940
	11th to 20th	Day	7% 4 1 5% 3 4 4 4 6% 9% 53%	2940
	21st to end	Day	6% 2 1 4 3 4 4 4 6% 9% 58%	2940
July	1st to 10th	Day	3 2 1 3 3 3 4 4 6% 9% 60%	8249
	11th to 20th	Day	4 1 1 3 2 3 4 4 5% 8% 66%	8250
	21st to end	Day	6% 3 1 5% 4 4 5% 5% 8% 10% 49%	8957
August	1st to 10th	Day	7% 2 1 3 3 3 4 4 7% 10% 54%	6216
	11th to 20th	Day	3 2 1 4 3 4 4 4 6% 8% 61%	5515
	21st to end	Day	7% 5% 2 6% 3 4 5% 4 6% 8% 51%	6093
September	1st to 10th	Day	6% 4 1 3 3 2 3 3 5% 7% 64%	2400
	11th to 20th	Day	8% 2 1 4 3 2 3 3 5% 7% 63%	2341
	21st to end	Day	7% 4 1 3 2 2 3 2 5% 8% 63%	2200
October	1st to 10th	Day	6% 3 1 2 2 1 2 2 3 4 74%	3371
	11th to 20th	Day	9% 4 1 4 3 3 4 2 5% 6% 58%	3250
	21st to end	Day	8% 5% 2 4 3 3 3 3 5% 7% 58%	3255
November	1st to 10th	Day	4 5% 2 4 3 4 4 3 6% 9% 56%	1853
	11th to 20th	Day	4 4 2 4 3 4 3 3 5% 9% 59%	1890
	21st to end	Day	5% 7% 2 5% 3 3 3 4 6% 6% 57%	1728
December	1st to 10th	Day	3 4 2 4 3 3 4 3 5% 6% 63%	2700
	11th to 20th	Day	3 5% 1 3 3 3 3 4 5% 9% 60%	3106
	21st to end	Day	5% 8% 3 6% 4 4 5% 3 6% 8% 47%	4092
January	1st to 10th	Night	3 8% 3 8% 5% 4 5% 4 6% 7% 47%	8201
	11th to 20th	Night	3 6% 3 7% 5% 4 5% 4 6% 7% 50%	8250
	21st to end	Night	2 6% 3 8% 5% 5% 5% 3 4 6% 52%	8746
February	1st to 10th	Night	4 9% 3 7% 5% 4 5% 4 6% 7% 46%	2730
	11th to 20th	Night	6% 9% 3 8% 5% 4 4 3 6% 7% 44%	2489
	21st to end	Night	4 7% 3 7% 4 3 4 4 6% 6% 52%	2076
March	1st to 10th	Night	8% 11% 3 5% 3 3 3 3 4 5% 53%	5494
	11th to 20th	Night	5% 6% 2 6% 3 3 4 3 5% 6% 56%	5340
	21st to end	Night	10% 9% 3 7% 4 4 5% 4 6% 8% 41%	5145
April	1st to 10th	Night	11% 6% 3 5% 4 3 4 3 5% 6% 50%	2100
	11th to 20th	Night	11% 7% 2 5% 4 4 4 3 5% 7% 47%	2077
	21st to end	Night	14% 7% 2 6% 5% 4 4 5% 5% 5% 43%	2042
May	1st to 10th	Night	13% 7% 3 6% 4 3 4 3 4 6% 48%	5189
	11th to 20th	Night	12% 5% 1 5% 3 3 4 4 6% 8% 48%	4701
	21st to end	Night	14% 5% 2 6% 4 3 3 4 6% 9% 45%	5181
June	1st to 10th	Night	7% 4 1 5% 4 4 4 5% 7% 8% 50%	1680
	11th to 20th	Night	8% 3 2 4 3 3 4 3 6% 9% 54%	1680
	21st to end	Night	5% 2 1 4 3 4 5% 4 7% 9% 56%	1680
July	1st to 10th	Night	4 3 2 5% 5% 5% 6% 5% 7% 8% 50%	4740
	11th to 20th	Night	4 2 1 4 3 4 4 4 6% 8% 61%	4740
	21st to end	Night	5% 4 2 7% 5% 6% 6% 5% 7% 10% 43%	5152
August	1st to 10th	Night	10% 3 2 5% 4 4 4 4 6% 9% 50%	3798
	11th to 20th	Night	2 2 1 4 4 5% 6% 5% 7% 9% 55%	4540
	21st to end	Night	8% 5% 2 7% 4 5% 5% 4 6% 8% 47%	5083
September	1st to 10th	Night	7% 4 2 4 3 2 3 3 5% 7% 60%	2000
	11th to 20th	Night	7% 4 2 4 3 3 3 3 3 7% 60%	2058
	21st to end	Night	8% 4 1 4 3 3 4 3 4 4 62%	2200
October	1st to 10th	Night	7% 2 1 2 2 2 2 2 3 4 73%	3811
	11th to 20th	Night	9% 3 1 3 3 3 4 3 5% 6% 59%	3898
	21st to end	Night	8% 5% 2 3 3 3 3 3 5% 7% 57%	4512
November	1st to 10th	Night	6% 5% 2 5% 3 3 3 3 6% 8% 55%	2665
	11th to 20th	Night	4 5% 2 4 4 4 4 4 6% 6% 56%	2730
	21st to end	Night	5% 7% 2 5% 3 4 3 3 5% 7% 57%	2888
December	1st to 10th	Night	3 4 2 5% 4 4 3 2 4 6% 63%	4710
	11th to 20th	Night	3 6% 2 5% 4 4 4 4 6% 8% 55%	5321
	21st to end	Night	6% 9% 3 7% 4 4 5% 4 5% 8% 46%	7128

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	33% 4 14% 29% 20%	4723
	11th to 20th	Day	34% 5% 14% 25% 16% 5%	4740
	21st to end	Day	26% 4 14% 30% 22% 4	5523
February	1st to 10th	Day	37% 5% 16% 24% 16% 3	1890
	11th to 20th	Day	36% 6% 11% 26% 16% 4	2027
	21st to end	Day	31% 3 13% 28% 20% 5%	1730
March	1st to 10th	Day	33% 4 6% 28% 25% 4	4600
	11th to 20th	Day	28% 4 13% 31% 23% 3	4866
	21st to end	Day	34% 7% 15% 30% 13% 1	6051
April	1st to 10th	Day	34% 6% 14% 26% 15% 5%	2520
	11th to 20th	Day	38% 6% 12% 20% 20% 4	2494
	21st to end	Day	36% 5% 12% 28% 17% 2	2576
May	1st to 10th	Day	33% 5% 12% 30% 16% 3	7743
	11th to 20th	Day	31% 6% 11% 26% 21% 6%	8195
	21st to end	Day	33% 6% 13% 27% 18% 3	9027
June	1st to 10th	Day	26% 8% 17% 27% 17% 5%	2940
	11th to 20th	Day	27% 6% 12% 24% 21% 10%	2940
	21st to end	Day	22% 5% 10% 26% 26% 11%	2940
July	1st to 10th	Day	18% 5% 8% 27% 26% 16%	8181
	11th to 20th	Day	16% 4 7% 27% 24% 21%	8175
	21st to end	Day	27% 6% 13% 19% 19% 16%	8759
August	1st to 10th	Day	25% 5% 13% 26% 22% 10%	4557
	11th to 20th	Day	24% 6% 10% 21% 24% 15%	4019
	21st to end	Day	23% 5% 10% 19% 25% 19%	4420
September	1st to 10th	Day	20% 4 7% 22% 30% 17%	2400
	11th to 20th	Day	21% 4 8% 24% 27% 15%	2341
	21st to end	Day	21% 4 7% 26% 33% 9%	2200
October	1st to 10th	Day	17% 3 7% 17% 31% 25%	3371
	11th to 20th	Day	27% 4 10% 29% 23% 7%	3250
	21st to end	Day	27% 3 11% 31% 23% 4	3255
November	1st to 10th	Day	25% 4 14% 27% 22% 7%	1853
	11th to 20th	Day	23% 4 13% 31% 25% 4	1890
	21st to end	Day	27% 4 12% 29% 25% 3	1728
December	1st to 10th	Day	21% 4 14% 34% 24% 2	2700
	11th to 20th	Day	21% 4 15% 39% 18% 2	3104
	21st to end	Day	34% 4 11% 35% 14% 1	4092
January	1st to 10th	Night	35% 5% 12% 33% 14% 2	8202
	11th to 20th	Night	32% 6% 15% 27% 16% 5%	8250
	21st to end	Night	33% 4 13% 30% 18% 2	8746
February	1st to 10th	Night	37% 6% 15% 26% 13% 2	2730
	11th to 20th	Night	38% 6% 13% 25% 15% 3	2489
	21st to end	Night	31% 6% 12% 28% 19% 3	2076
March	1st to 10th	Night	34% 4 6% 27% 25% 4	5494
	11th to 20th	Night	28% 4 12% 25% 28% 2	5340
	21st to end	Night	40% 5% 21% 21% 12% 1	5145
April	1st to 10th	Night	34% 6% 13% 26% 16% 4	2100
	11th to 20th	Night	35% 6% 13% 25% 18% 4	2077
	21st to end	Night	42% 6% 10% 27% 15% 1	2042
May	1st to 10th	Night	38% 5% 10% 28% 18% 1	5190
	11th to 20th	Night	33% 6% 14% 29% 12% 6%	4702
	21st to end	Night	35% 6% 17% 29% 11% 2	5182
June	1st to 10th	Night	28% 8% 23% 24% 13% 4	1680
	11th to 20th	Night	26% 7% 16% 25% 19% 7%	1680
	21st to end	Night	22% 6% 15% 26% 21% 9%	1680
July	1st to 10th	Night	27% 7% 13% 26% 20% 8%	4700
	11th to 20th	Night	21% 5% 14% 26% 20% 14%	4692
	21st to end	Night	35% 7% 16% 19% 17% 7%	5038
August	1st to 10th	Night	34% 6% 14% 22% 18% 6%	2781
	11th to 20th	Night	26% 9% 14% 23% 19% 9%	3312
	21st to end	Night	26% 7% 13% 20% 23% 13%	3687
September	1st to 10th	Night	24% 4 7% 25% 25% 14%	2000
	11th to 20th	Night	25% 5% 8% 25% 24% 12%	2058
	21st to end	Night	25% 5% 7% 26% 26% 12%	2200
October	1st to 10th	Night	17% 3 7% 17% 31% 24%	3811
	11th to 20th	Night	26% 4 13% 29% 22% 7%	3898
	21st to end	Night	26% 4 10% 30% 21% 8%	4512
November	1st to 10th	Night	27% 4 13% 26% 24% 6%	2665
	11th to 20th	Night	27% 5% 10% 31% 22% 6%	2730
	21st to end	Night	28% 4 11% 31% 21% 5%	2888
December	1st to 10th	Night	24% 4 14% 35% 21% 2	4710
	11th to 20th	Night	26% 5% 12% 39% 16% 2	5322
	21st to end	Night	36% 5% 11% 33% 14% 1	7128

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% 10% 28% 32% 16% 4	330
	11th to 20th	Day	12% 13% 39% 25% 11% 1	330
	21st to end	Day	6% 11% 45% 29% 7% 2	363
February	1st to 10th	Day	11% 13% 44% 25% 6% 1	330
	11th to 20th	Day	9% 12% 42% 28% 8% 1	330
	21st to end	Day	10% 20% 34% 29% 6% 1	273
March	1st to 10th	Day	11% 13% 29% 33% 13% 2	330
	11th to 20th	Day	12% 15% 31% 28% 12% 2	426
	21st to end	Day	15% 14% 34% 26% 9% 3	594
April	1st to 10th	Day	14% 16% 35% 23% 10% 2	540
	11th to 20th	Day	15% 21% 30% 22% 9% 2	532
	21st to end	Day	13% 13% 27% 29% 15% 3	596
May	1st to 10th	Day	15% 10% 27% 28% 16% 3	753
	11th to 20th	Day	17% 9% 23% 27% 19% 5%	775
	21st to end	Day	14% 8% 25% 28% 20% 5%	844
June	1st to 10th	Day	7% 4 22% 36% 24% 7%	780
	11th to 20th	Day	9% 7% 29% 33% 18% 4	780
	21st to end	Day	7% 4 24% 34% 26% 5%	780
July	1st to 10th	Day	4 4 18% 37% 29% 8%	771
	11th to 20th	Day	6% 3 17% 36% 31% 8%	768
	21st to end	Day	6% 2 15% 33% 37% 7%	849
August	1st to 10th	Day	5% 2 19% 37% 29% 7%	709
	11th to 20th	Day	4 4 21% 31% 28% 13%	557
	21st to end	Day	5% 3 23% 32% 26% 11%	620
September	1st to 10th	Day	7% 5% 18% 33% 25% 12%	530
	11th to 20th	Day	7% 3 22% 26% 29% 12%	471
	21st to end	Day	7% 6% 20% 32% 21% 15%	330
October	1st to 10th	Day	12% 6% 22% 24% 22% 15%	330
	11th to 20th	Day	10% 12% 29% 25% 17% 7%	330
	21st to end	Day	9% 11% 31% 29% 14% 5%	363
November	1st to 10th	Day	9% 8% 32% 32% 15% 5%	330
	11th to 20th	Day	6% 10% 33% 35% 15% 2	330
	21st to end	Day	8% 10% 29% 35% 14% 5%	330
December	1st to 10th	Day	6% 18% 34% 29% 12% 2	330
	11th to 20th	Day	11% 13% 38% 30% 7% 1	330
	21st to end	Day	12% 15% 30% 28% 13% 1	363
January	1st to 10th	Night	7% 10% 37% 36% 10% 1	1050
	11th to 20th	Night	7% 14% 42% 30% 6% 1	1050
	21st to end	Night	9% 7% 43% 35% 6%	1055
February	1st to 10th	Night	8% 9% 47% 31% 4	840
	11th to 20th	Night	11% 7% 43% 34% 5%	824
	21st to end	Night	7% 13% 45% 29% 5%	692
March	1st to 10th	Night	10% 10% 41% 33% 6%	840
	11th to 20th	Night	9% 9% 34% 43% 6%	840
	21st to end	Night	13% 11% 36% 35% 4 1	718
April	1st to 10th	Night	12% 12% 38% 34% 5%	630
	11th to 20th	Night	13% 9% 39% 33% 4	623
	21st to end	Night	17% 9% 30% 35% 9%	630
May	1st to 10th	Night	17% 8% 27% 36% 12%	630
	11th to 20th	Night	16% 5% 26% 41% 11%	621
	21st to end	Night	13% 7% 30% 36% 13%	683
June	1st to 10th	Night	8% 4 31% 39% 17% 1	630
	11th to 20th	Night	9% 4 38% 42% 7%	630
	21st to end	Night	5% 4 32% 47% 12%	630
July	1st to 10th	Night	5% 3 23% 50% 18% 1	615
	11th to 20th	Night	4 1 21% 56% 17%	612
	21st to end	Night	4 3 17% 53% 22% 1	690
August	1st to 10th	Night	6% 2 22% 50% 19%	627
	11th to 20th	Night	4 2 22% 53% 19%	624
	21st to end	Night	5% 3 21% 51% 21%	687
September	1st to 10th	Night	8% 4 21% 49% 17% 1	600
	11th to 20th	Night	8% 3 23% 45% 20% 1	600
	21st to end	Night	10% 3 29% 44% 14%	600
October	1st to 10th	Night	14% 4 28% 38% 16% 1	730
	11th to 20th	Night	12% 5% 30% 44% 10%	800
	21st to end	Night	10% 6% 34% 38% 11% 1	1039
November	1st to 10th	Night	9% 6% 33% 42% 10% 1	1025
	11th to 20th	Night	5% 10% 40% 38% 6%	1050
	21st to end	Night	8% 8% 34% 43% 7%	1050
December	1st to 10th	Night	7% 9% 44% 33% 6%	1050
	11th to 20th	Night	9% 8% 41% 36% 6%	1050
	21st to end	Night	10% 11% 41% 32% 6%	1155

Page generated at 2026-08-27 02:07:15. Version ac07

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