Connecticut Star Party
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Connecticut Star Party clear sky chart from 2005-11-06 to 2024-07-03.

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	17% 8% 3 7% 5% 4 5% 4 5% 7% 36%	89473
	Night	17% 9% 3 6% 4 4 4 4 5% 6% 38%	89744
Transparency	Day	47% 4 11% 23% 13% 2	89192
	Night	46% 4 11% 23% 14% 2	89579
Seeing	Day	25% 19% 30% 18% 7% 2	14470
	Night	23% 18% 30% 22% 7% 1	23560

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	13% 9% 3 5% 5% 5% 4 3 5% 6% 42%	2517
	11th to 20th	Day	15% 10% 4 10% 6% 5% 5% 3 4 6% 32%	2520
	21st to end	Day	22% 13% 6% 8% 4 4 4 3 4 5% 29%	2868
February	1st to 10th	Day	16% 10% 3 7% 7% 5% 5% 4 5% 6% 33%	1739
	11th to 20th	Day	13% 8% 3 7% 6% 5% 4 4 5% 6% 38%	1848
	21st to end	Day	18% 12% 3 7% 4 5% 3 3 4 6% 35%	1570
March	1st to 10th	Day	24% 13% 3 7% 4 4 3 2 4 4 31%	3116
	11th to 20th	Day	11% 8% 3 7% 7% 6% 6% 4 6% 7% 35%	3271
	21st to end	Day	20% 8% 3 7% 4 4 4 3 5% 7% 35%	4166
April	1st to 10th	Day	18% 10% 3 7% 4 5% 5% 4 5% 6% 35%	2280
	11th to 20th	Day	17% 8% 2 7% 4 5% 5% 3 5% 6% 39%	2254
	21st to end	Day	19% 8% 3 7% 4 4 4 4 5% 6% 37%	2374
May	1st to 10th	Day	27% 10% 2 6% 4 3 4 3 4 7% 28%	4106
	11th to 20th	Day	22% 8% 3 7% 5% 4 4 3 6% 7% 32%	4352
	21st to end	Day	13% 6% 2 6% 4 4 5% 4 6% 9% 42%	4837
June	1st to 10th	Day	17% 7% 2 6% 5% 5% 6% 5% 6% 8% 33%	2660
	11th to 20th	Day	16% 7% 2 6% 6% 5% 5% 4 7% 9% 34%	2660
	21st to end	Day	14% 7% 3 8% 5% 5% 5% 4 6% 9% 34%	2660
July	1st to 10th	Day	12% 7% 2 6% 5% 5% 6% 5% 6% 7% 39%	2548
	11th to 20th	Day	12% 6% 2 6% 5% 5% 6% 4 7% 9% 40%	2520
	21st to end	Day	12% 7% 2 7% 5% 5% 6% 5% 7% 7% 38%	2744
August	1st to 10th	Day	12% 7% 2 7% 5% 5% 6% 5% 7% 9% 35%	2449
	11th to 20th	Day	13% 7% 2 6% 5% 6% 6% 4 7% 9% 37%	2127
	21st to end	Day	13% 6% 2 7% 5% 4 4 4 6% 8% 41%	2376
September	1st to 10th	Day	14% 8% 3 7% 4 4 5% 4 6% 6% 40%	2160
	11th to 20th	Day	13% 6% 3 5% 3 3 4 3 5% 7% 48%	2052
	21st to end	Day	17% 7% 2 5% 4 4 4 4 5% 7% 41%	1980
October	1st to 10th	Day	22% 8% 2 6% 4 4 5% 2 4 5% 38%	1923
	11th to 20th	Day	14% 7% 2 7% 4 4 4 4 6% 7% 42%	1796
	21st to end	Day	23% 7% 2 6% 4 4 4 4 6% 5% 34%	1782
November	1st to 10th	Day	14% 7% 3 6% 3 3 3 3 5% 7% 46%	1671
	11th to 20th	Day	19% 7% 2 5% 4 3 4 4 5% 6% 42%	1710
	21st to end	Day	17% 9% 3 6% 4 4 3 3 5% 6% 41%	1639
December	1st to 10th	Day	18% 8% 4 8% 4 4 5% 4 6% 6% 33%	1520
	11th to 20th	Day	21% 8% 3 6% 3 3 3 4 5% 6% 38%	1906
	21st to end	Day	18% 12% 4 9% 6% 5% 4 4 5% 7% 26%	2772
January	1st to 10th	Night	15% 8% 2 5% 4 4 4 4 6% 6% 42%	4429
	11th to 20th	Night	15% 9% 4 8% 6% 5% 4 3 4 5% 37%	4440
	21st to end	Night	22% 14% 4 7% 5% 4 4 3 5% 4 29%	4785
February	1st to 10th	Night	16% 10% 3 6% 4 4 5% 4 5% 6% 36%	2439
	11th to 20th	Night	14% 9% 3 7% 5% 5% 5% 4 6% 6% 36%	2218
	21st to end	Night	18% 8% 3 7% 4 4 3 4 5% 6% 37%	1884
March	1st to 10th	Night	23% 12% 3 6% 4 4 4 3 4 5% 32%	3724
	11th to 20th	Night	11% 8% 3 7% 5% 5% 5% 4 6% 7% 39%	3682
	21st to end	Night	19% 10% 3 7% 4 4 3 3 5% 5% 37%	3466
April	1st to 10th	Night	17% 10% 4 7% 5% 4 6% 5% 5% 6% 32%	1900
	11th to 20th	Night	18% 8% 2 6% 6% 4 4 3 5% 6% 38%	1875
	21st to end	Night	19% 9% 3 6% 4 4 3 4 4 6% 39%	1805
May	1st to 10th	Night	26% 10% 3 7% 4 4 4 3 5% 7% 28%	2834
	11th to 20th	Night	20% 10% 3 8% 4 5% 4 3 5% 7% 31%	2570
	21st to end	Night	16% 6% 3 6% 4 4 4 4 5% 8% 42%	2738
June	1st to 10th	Night	17% 8% 2 6% 4 3 4 3 5% 6% 42%	1520
	11th to 20th	Night	14% 7% 2 6% 5% 4 4 4 8% 9% 36%	1520
	21st to end	Night	14% 6% 2 6% 4 3 5% 3 6% 9% 42%	1520
July	1st to 10th	Night	14% 6% 2 5% 4 4 5% 4 5% 8% 43%	1456
	11th to 20th	Night	14% 6% 3 6% 4 4 4 4 7% 9% 39%	1440
	21st to end	Night	10% 6% 1 6% 7% 4 6% 4 6% 7% 43%	1574
August	1st to 10th	Night	10% 5% 3 6% 4 4 4 4 8% 8% 45%	1470
	11th to 20th	Night	13% 6% 2 7% 5% 5% 5% 5% 7% 7% 37%	1769
	21st to end	Night	16% 6% 2 4 4 4 4 3 5% 7% 45%	1980
September	1st to 10th	Night	14% 7% 3 6% 5% 4 3 3 5% 6% 44%	1800
	11th to 20th	Night	13% 6% 3 5% 2 3 3 2 4 6% 54%	1908
	21st to end	Night	17% 7% 2 5% 3 3 4 3 4 6% 45%	1980
October	1st to 10th	Night	20% 7% 2 6% 4 3 4 2 4 5% 41%	2034
	11th to 20th	Night	14% 7% 2 7% 4 4 4 3 5% 6% 43%	2162
	21st to end	Night	22% 8% 2 6% 4 3 4 3 5% 6% 36%	2574
November	1st to 10th	Night	15% 7% 2 5% 3 4 3 4 5% 6% 46%	2407
	11th to 20th	Night	17% 8% 2 6% 3 4 3 4 6% 7% 40%	2470
	21st to end	Night	14% 8% 2 6% 5% 5% 4 3 6% 6% 41%	2539
December	1st to 10th	Night	19% 8% 3 7% 5% 4 4 4 5% 6% 34%	2660
	11th to 20th	Night	19% 8% 2 6% 4 5% 4 4 5% 6% 35%	3288
	21st to end	Night	21% 11% 3 7% 4 4 4 4 5% 6% 31%	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	43% 4 9% 34% 8% 2	2518
	11th to 20th	Day	53% 4 10% 24% 8% 1	2520
	21st to end	Day	59% 3 7% 21% 9% 1	2868
February	1st to 10th	Day	51% 4 12% 19% 12% 1	1739
	11th to 20th	Day	45% 5% 8% 23% 15% 2	1857
	21st to end	Day	51% 4 10% 20% 12% 3	1570
March	1st to 10th	Day	57% 2 10% 17% 12% 2	3119
	11th to 20th	Day	45% 5% 10% 29% 10% 2	3271
	21st to end	Day	50% 3 5% 16% 21% 5%	4166
April	1st to 10th	Day	49% 5% 8% 20% 14% 3	2280
	11th to 20th	Day	46% 4 9% 22% 16% 2	2254
	21st to end	Day	47% 4 9% 20% 16% 4	2374
May	1st to 10th	Day	56% 4 12% 16% 11% 1	4120
	11th to 20th	Day	52% 3 14% 21% 9% 1	4356
	21st to end	Day	39% 4 11% 28% 16% 1	4837
June	1st to 10th	Day	46% 6% 13% 23% 12% 1	2660
	11th to 20th	Day	44% 5% 14% 25% 11% 1	2660
	21st to end	Day	45% 6% 13% 23% 12% 1	2660
July	1st to 10th	Day	43% 5% 12% 21% 17% 1	2478
	11th to 20th	Day	40% 5% 15% 27% 12% 1	2445
	21st to end	Day	43% 5% 13% 21% 16% 2	2591
August	1st to 10th	Day	44% 6% 13% 24% 13% 1	2435
	11th to 20th	Day	42% 6% 16% 26% 11% 1	2127
	21st to end	Day	40% 5% 12% 25% 17% 1	2376
September	1st to 10th	Day	43% 5% 11% 24% 15% 2	2160
	11th to 20th	Day	35% 4 10% 25% 24% 2	2052
	21st to end	Day	41% 5% 10% 23% 18% 3	1980
October	1st to 10th	Day	48% 4 8% 23% 13% 3	1923
	11th to 20th	Day	40% 5% 12% 28% 13% 2	1796
	21st to end	Day	51% 4 10% 19% 13% 3	1782
November	1st to 10th	Day	37% 4 13% 26% 17% 3	1671
	11th to 20th	Day	42% 4 11% 23% 17% 3	1710
	21st to end	Day	44% 3 13% 26% 12% 2	1639
December	1st to 10th	Day	51% 4 14% 18% 13% 1	1520
	11th to 20th	Day	46% 5% 14% 21% 12% 2	1906
	21st to end	Day	57% 3 9% 20% 11%	2772
January	1st to 10th	Night	42% 3 11% 30% 11% 3	4429
	11th to 20th	Night	48% 4 11% 23% 11% 3	4440
	21st to end	Night	58% 3 8% 19% 10% 1	4785
February	1st to 10th	Night	48% 4 12% 22% 12% 2	2439
	11th to 20th	Night	46% 5% 9% 19% 18% 3	2220
	21st to end	Night	48% 4 8% 23% 13% 5%	1884
March	1st to 10th	Night	56% 3 8% 20% 11% 2	3734
	11th to 20th	Night	43% 4 15% 23% 14% 2	3683
	21st to end	Night	49% 3 6% 15% 22% 5%	3466
April	1st to 10th	Night	49% 4 9% 21% 14% 2	1900
	11th to 20th	Night	48% 4 9% 20% 18% 1	1875
	21st to end	Night	46% 3 9% 23% 16% 4	1805
May	1st to 10th	Night	57% 3 12% 16% 9% 2	2840
	11th to 20th	Night	55% 4 13% 18% 9% 2	2571
	21st to end	Night	42% 4 16% 24% 14% 1	2739
June	1st to 10th	Night	44% 4 10% 26% 14% 1	1520
	11th to 20th	Night	42% 4 17% 26% 10% 1	1520
	21st to end	Night	39% 6% 14% 27% 14% 1	1520
July	1st to 10th	Night	39% 5% 15% 25% 15% 2	1416
	11th to 20th	Night	40% 5% 15% 31% 8% 1	1392
	21st to end	Night	38% 6% 16% 22% 16% 3	1486
August	1st to 10th	Night	35% 6% 18% 26% 14% 1	1460
	11th to 20th	Night	42% 7% 15% 25% 10%	1769
	21st to end	Night	38% 5% 11% 27% 18% 1	1980
September	1st to 10th	Night	41% 5% 10% 27% 16% 1	1800
	11th to 20th	Night	33% 3 12% 26% 25% 1	1908
	21st to end	Night	41% 4 8% 24% 21% 2	1980
October	1st to 10th	Night	46% 4 11% 23% 14% 2	2034
	11th to 20th	Night	40% 4 12% 29% 13% 1	2162
	21st to end	Night	48% 4 12% 21% 13% 1	2574
November	1st to 10th	Night	39% 4 11% 22% 21% 4	2407
	11th to 20th	Night	43% 4 11% 22% 18% 3	2470
	21st to end	Night	42% 3 14% 29% 11% 1	2539
December	1st to 10th	Night	49% 5% 11% 22% 12% 1	2660
	11th to 20th	Night	48% 5% 13% 18% 15% 2	3288
	21st to end	Night	54% 3 9% 22% 12%	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	31% 28% 26% 13% 2	180
	11th to 20th	Day	33% 30% 26% 9% 1	180
	21st to end	Day	21% 35% 31% 10% 3 1	225
February	1st to 10th	Day	35% 31% 25% 7% 1	299
	11th to 20th	Day	30% 30% 31% 8% 1	456
	21st to end	Day	35% 24% 29% 10% 3	382
March	1st to 10th	Day	29% 24% 34% 11% 2	460
	11th to 20th	Day	30% 28% 30% 10% 2 1	460
	21st to end	Day	34% 23% 30% 8% 5% 1	506
April	1st to 10th	Day	30% 25% 28% 9% 6% 1	460
	11th to 20th	Day	31% 26% 26% 12% 4 1	452
	21st to end	Day	30% 18% 35% 12% 3 1	460
May	1st to 10th	Day	35% 21% 25% 13% 5% 2	463
	11th to 20th	Day	23% 21% 31% 20% 5% 1	487
	21st to end	Day	23% 12% 31% 22% 9% 2	529
June	1st to 10th	Day	22% 14% 33% 19% 10% 2	490
	11th to 20th	Day	19% 13% 33% 24% 9% 1	490
	21st to end	Day	17% 17% 31% 25% 8% 1	490
July	1st to 10th	Day	15% 12% 32% 26% 13% 2	453
	11th to 20th	Day	14% 7% 32% 32% 12% 3	444
	21st to end	Day	14% 10% 37% 26% 12% 2	488
August	1st to 10th	Day	14% 9% 31% 30% 12% 5%	446
	11th to 20th	Day	15% 10% 29% 28% 11% 7%	439
	21st to end	Day	14% 13% 29% 25% 13% 6%	495
September	1st to 10th	Day	21% 12% 25% 20% 16% 6%	450
	11th to 20th	Day	16% 13% 28% 22% 11% 9%	450
	21st to end	Day	20% 14% 33% 19% 9% 4	450
October	1st to 10th	Day	30% 11% 27% 16% 12% 4	450
	11th to 20th	Day	21% 21% 28% 21% 7% 1	448
	21st to end	Day	30% 19% 26% 18% 6% 1	396
November	1st to 10th	Day	25% 18% 26% 21% 9% 1	365
	11th to 20th	Day	33% 22% 26% 14% 4 1	370
	21st to end	Day	27% 25% 27% 15% 4	299
December	1st to 10th	Day	28% 30% 28% 9% 5%	180
	11th to 20th	Day	38% 25% 27% 8% 2	180
	21st to end	Day	29% 29% 27% 13% 3	198
January	1st to 10th	Night	23% 26% 34% 14% 3	760
	11th to 20th	Night	29% 24% 31% 14% 2	760
	21st to end	Night	23% 25% 34% 15% 2	836
February	1st to 10th	Night	27% 24% 31% 17% 2	760
	11th to 20th	Night	25% 28% 35% 11% 1	743
	21st to end	Night	31% 25% 27% 15% 3	628
March	1st to 10th	Night	25% 24% 33% 15% 2	760
	11th to 20th	Night	23% 27% 31% 16% 3	760
	21st to end	Night	26% 25% 29% 15% 4	836
April	1st to 10th	Night	26% 21% 32% 18% 3	760
	11th to 20th	Night	25% 21% 32% 15% 6%	751
	21st to end	Night	25% 21% 32% 17% 5%	665
May	1st to 10th	Night	30% 16% 29% 19% 6% 1	570
	11th to 20th	Night	22% 16% 37% 20% 4	423
	21st to end	Night	20% 9% 29% 32% 9% 1	411
June	1st to 10th	Night	21% 9% 30% 30% 9% 1	380
	11th to 20th	Night	20% 8% 30% 29% 12% 1	380
	21st to end	Night	19% 6% 28% 34% 12% 1	380
July	1st to 10th	Night	18% 6% 21% 36% 18%	354
	11th to 20th	Night	16% 5% 24% 39% 16% 1	348
	21st to end	Night	12% 5% 27% 40% 16%	394
August	1st to 10th	Night	11% 4 28% 40% 16% 1	396
	11th to 20th	Night	16% 4 22% 36% 19% 2	705
	21st to end	Night	18% 5% 24% 34% 18% 2	792
September	1st to 10th	Night	18% 7% 29% 31% 13% 3	720
	11th to 20th	Night	17% 8% 26% 29% 18% 3	720
	21st to end	Night	23% 9% 25% 27% 14% 3	720
October	1st to 10th	Night	23% 15% 24% 25% 10% 2	720
	11th to 20th	Night	19% 17% 30% 24% 9% 1	720
	21st to end	Night	30% 16% 30% 18% 6%	792
November	1st to 10th	Night	21% 18% 31% 21% 8% 1	740
	11th to 20th	Night	24% 22% 30% 17% 7% 1	760
	21st to end	Night	23% 22% 31% 20% 5% 1	760
December	1st to 10th	Night	28% 22% 29% 16% 4 1	760
	11th to 20th	Night	25% 27% 28% 18% 3	760
	21st to end	Night	29% 23% 32% 13% 2	836

Page generated at 2024-06-29 22:08:54. Version ac07

Copyright © 2024 Attilla Danko.