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 2024-10-25.

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	7% 5% 2 5% 3 4 4 4 6% 8% 54%	101329
	Night	7% 6% 2 5% 4 4 4 4 5% 7% 52%	97683
Transparency	Day	28% 5% 12% 26% 20% 8%	101070
	Night	30% 6% 14% 27% 18% 5%	97532
Seeing	Day	9% 8% 26% 31% 20% 6%	15749
	Night	9% 7% 34% 40% 11%	25697

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% 3 7% 5% 4 4 3 5% 7% 53%	2538
	11th to 20th	Day	3 10% 3 8% 6% 5% 5% 4 6% 6% 44%	2540
	21st to end	Day	3 5% 2 4 3 3 3 3 5% 7% 63%	2963
February	1st to 10th	Day	5% 9% 4 8% 5% 4 5% 3 5% 6% 46%	1710
	11th to 20th	Day	5% 8% 3 7% 4 4 5% 4 5% 8% 47%	1819
	21st to end	Day	5% 8% 3 6% 4 3 3 3 5% 7% 52%	1570
March	1st to 10th	Day	6% 8% 3 7% 3 3 4 3 6% 7% 51%	3130
	11th to 20th	Day	6% 5% 2 5% 3 3 4 3 4 6% 58%	3321
	21st to end	Day	9% 7% 2 6% 4 5% 4 4 6% 8% 43%	4129
April	1st to 10th	Day	9% 7% 3 5% 4 3 4 4 6% 7% 47%	2280
	11th to 20th	Day	13% 7% 2 6% 4 5% 4 4 6% 8% 40%	2251
	21st to end	Day	10% 8% 2 5% 4 4 3 4 6% 8% 46%	2330
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	11% 4 2 3 3 2 3 3 5% 5% 59%	1962
	11th to 20th	Day	8% 4 1 4 3 3 5% 3 5% 6% 60%	1900
	21st to end	Day	7% 4 2 4 2 3 3 4 6% 7% 59%	1861
November	1st to 10th	Day	3 6% 2 4 3 4 4 3 6% 8% 56%	1673
	11th to 20th	Day	4 4 2 4 3 4 3 3 5% 9% 58%	1710
	21st to end	Day	5% 7% 2 4 3 3 3 3 6% 6% 58%	1564
December	1st to 10th	Day	4 6% 2 5% 3 4 5% 4 7% 8% 51%	1520
	11th to 20th	Day	5% 6% 2 3 4 4 4 4 5% 9% 56%	1926
	21st to end	Day	6% 11% 3 6% 4 4 4 3 4 7% 48%	2794
January	1st to 10th	Night	3 7% 3 7% 5% 4 4 4 6% 8% 50%	4417
	11th to 20th	Night	3 6% 4 7% 4 4 5% 4 6% 8% 50%	4430
	21st to end	Night	4 5% 2 6% 4 5% 5% 4 4 7% 55%	4731
February	1st to 10th	Night	4 10% 3 7% 5% 4 5% 4 6% 7% 46%	2470
	11th to 20th	Night	6% 9% 3 7% 5% 4 5% 4 6% 7% 45%	2247
	21st to end	Night	5% 8% 3 7% 4 3 4 4 6% 6% 50%	1884
March	1st to 10th	Night	5% 12% 3 5% 4 3 3 3 5% 6% 51%	3734
	11th to 20th	Night	6% 7% 3 6% 4 3 3 3 4 6% 54%	3650
	21st to end	Night	9% 9% 3 7% 4 3 4 4 6% 7% 43%	3513
April	1st to 10th	Night	12% 6% 3 4 4 3 3 3 5% 6% 50%	1900
	11th to 20th	Night	11% 7% 2 5% 4 4 4 3 6% 7% 46%	1877
	21st to end	Night	15% 6% 2 6% 5% 4 4 5% 5% 5% 43%	1848
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	12% 4 1 3 3 3 3 3 4 7% 57%	2213
	11th to 20th	Night	9% 3 1 3 3 3 3 3 5% 5% 61%	2280
	21st to end	Night	8% 6% 2 4 3 4 3 3 4 6% 56%	2581
November	1st to 10th	Night	6% 5% 2 4 3 3 3 3 6% 8% 56%	2405
	11th to 20th	Night	4 5% 2 5% 4 4 4 4 6% 6% 55%	2470
	21st to end	Night	5% 7% 2 5% 3 3 3 3 5% 7% 57%	2612
December	1st to 10th	Night	5% 7% 3 6% 4 3 4 3 4 7% 53%	2660
	11th to 20th	Night	4 6% 2 4 3 3 4 4 6% 8% 57%	3271
	21st to end	Night	7% 10% 3 6% 4 4 5% 4 5% 7% 47%	4873

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	31% 5% 14% 29% 20%	2539
	11th to 20th	Day	39% 7% 17% 21% 15% 2	2540
	21st to end	Day	22% 4 21% 34% 15% 3	2963
February	1st to 10th	Day	39% 5% 16% 23% 15% 2	1710
	11th to 20th	Day	35% 7% 12% 25% 17% 4	1829
	21st to end	Day	33% 3 14% 27% 18% 5%	1570
March	1st to 10th	Day	31% 5% 8% 28% 22% 4	3130
	11th to 20th	Day	28% 5% 17% 35% 14% 2	3321
	21st to end	Day	37% 8% 15% 30% 10% 1	4129
April	1st to 10th	Day	35% 7% 15% 25% 14% 5%	2280
	11th to 20th	Day	39% 6% 13% 21% 17% 4	2254
	21st to end	Day	35% 5% 12% 28% 18% 2	2330
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	27% 5% 10% 23% 26% 10%	1962
	11th to 20th	Day	26% 5% 10% 28% 24% 8%	1900
	21st to end	Day	23% 4 14% 32% 21% 6%	1861
November	1st to 10th	Day	25% 4 15% 26% 22% 8%	1673
	11th to 20th	Day	24% 4 13% 31% 24% 4	1710
	21st to end	Day	26% 4 12% 28% 26% 4	1564
December	1st to 10th	Day	28% 6% 17% 26% 19% 3	1520
	11th to 20th	Day	25% 5% 13% 38% 18% 1	1924
	21st to end	Day	36% 5% 12% 31% 14% 2	2794
January	1st to 10th	Night	30% 5% 13% 37% 13% 1	4417
	11th to 20th	Night	30% 8% 20% 22% 17% 3	4430
	21st to end	Night	28% 5% 21% 33% 12% 1	4731
February	1st to 10th	Night	37% 6% 16% 26% 13% 2	2470
	11th to 20th	Night	36% 7% 14% 25% 15% 3	2247
	21st to end	Night	33% 6% 13% 27% 18% 3	1884
March	1st to 10th	Night	33% 5% 8% 28% 23% 3	3734
	11th to 20th	Night	31% 5% 16% 30% 16% 2	3650
	21st to end	Night	39% 6% 21% 24% 9% 1	3513
April	1st to 10th	Night	34% 7% 13% 25% 16% 5%	1900
	11th to 20th	Night	36% 6% 13% 25% 16% 4	1877
	21st to end	Night	41% 6% 9% 28% 15% 1	1848
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	28% 5% 12% 21% 25% 9%	2213
	11th to 20th	Night	26% 4 11% 28% 21% 10%	2280
	21st to end	Night	28% 5% 12% 27% 19% 8%	2581
November	1st to 10th	Night	26% 4 13% 26% 24% 6%	2405
	11th to 20th	Night	28% 5% 11% 31% 21% 6%	2470
	21st to end	Night	28% 4 10% 31% 22% 5%	2612
December	1st to 10th	Night	31% 5% 14% 28% 18% 4	2660
	11th to 20th	Night	24% 6% 15% 36% 18% 1	3272
	21st to end	Night	36% 5% 12% 32% 13% 2	4873

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	10% 6% 30% 31% 19% 5%	270
	11th to 20th	Day	10% 12% 38% 27% 12% 1	270
	21st to end	Day	6% 7% 49% 27% 7% 3	297
February	1st to 10th	Day	11% 13% 45% 25% 6%	270
	11th to 20th	Day	9% 13% 43% 26% 8% 1	270
	21st to end	Day	10% 20% 34% 31% 5%	225
March	1st to 10th	Day	8% 12% 30% 35% 13% 1	270
	11th to 20th	Day	12% 12% 32% 29% 13% 3	356
	21st to end	Day	15% 13% 34% 26% 9% 3	506
April	1st to 10th	Day	15% 15% 35% 24% 10% 1	460
	11th to 20th	Day	15% 21% 29% 24% 9% 2	452
	21st to end	Day	12% 13% 27% 29% 16% 4	510
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	9% 11% 33% 29% 14% 5%	311
November	1st to 10th	Day	8% 7% 29% 35% 15% 6%	270
	11th to 20th	Day	6% 11% 31% 35% 15% 2	270
	21st to end	Day	9% 9% 31% 36% 11% 4	270
December	1st to 10th	Day	7% 18% 31% 32% 11% 1	270
	11th to 20th	Day	10% 12% 37% 32% 7% 1	270
	21st to end	Day	12% 16% 29% 27% 14% 1	297
January	1st to 10th	Night	7% 10% 37% 35% 11% 1	950
	11th to 20th	Night	7% 13% 42% 32% 6% 1	950
	21st to end	Night	9% 6% 44% 33% 7%	955
February	1st to 10th	Night	9% 8% 47% 31% 5% 1	760
	11th to 20th	Night	11% 6% 43% 35% 5%	744
	21st to end	Night	8% 13% 45% 30% 5%	628
March	1st to 10th	Night	9% 9% 42% 34% 6%	760
	11th to 20th	Night	9% 8% 34% 43% 6%	760
	21st to end	Night	13% 10% 37% 35% 4 1	650
April	1st to 10th	Night	13% 12% 38% 33% 5%	570
	11th to 20th	Night	14% 9% 39% 33% 5%	563
	21st to end	Night	17% 8% 30% 35% 10%	570
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	957
November	1st to 10th	Night	9% 5% 32% 42% 11% 1	925
	11th to 20th	Night	5% 10% 40% 38% 7% 1	950
	21st to end	Night	8% 8% 34% 42% 7%	950
December	1st to 10th	Night	8% 9% 45% 33% 5%	950
	11th to 20th	Night	8% 8% 41% 37% 6%	950
	21st to end	Night	11% 11% 41% 32% 6%	1045

Page generated at 2024-10-22 18:20:59. Version ac07

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