Quincy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Quincy clear sky chart from 2005-11-06 to 2024-11-02.

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	5% 7% 2 4 3 3 3 3 4 5% 63%	101307
	Night	6% 8% 2 5% 3 3 3 3 5% 6% 57%	97869
Transparency	Day	26% 2 7% 20% 24% 21%	101056
	Night	30% 2 9% 21% 22% 16%	97710
Seeing	Day	13% 16% 28% 25% 15% 4	15043
	Night	11% 8% 18% 38% 24% 2	24281

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	7% 16% 3 8% 5% 5% 5% 4 5% 7% 36%	2539
	11th to 20th	Day	8% 15% 3 10% 6% 6% 5% 4 4 5% 34%	2671
	21st to end	Day	9% 17% 4 8% 5% 4 5% 3 5% 6% 33%	3146
February	1st to 10th	Day	9% 10% 3 6% 4 3 4 4 5% 7% 45%	1710
	11th to 20th	Day	5% 15% 3 6% 5% 3 3 2 6% 7% 46%	1772
	21st to end	Day	6% 17% 2 6% 4 3 4 3 5% 6% 45%	1570
March	1st to 10th	Day	6% 28% 6% 9% 4 4 3 3 4 5% 27%	3195
	11th to 20th	Day	5% 12% 2 3 3 3 3 3 4 6% 56%	3490
	21st to end	Day	7% 18% 4 9% 6% 5% 4 3 5% 6% 34%	3997
April	1st to 10th	Day	7% 13% 3 6% 4 3 4 4 7% 8% 42%	2280
	11th to 20th	Day	7% 10% 2 5% 3 3 4 3 5% 7% 51%	2249
	21st to end	Day	7% 7% 1 4 3 4 4 4 5% 7% 54%	2280
May	1st to 10th	Day	4 7% 1 4 2 2 2 2 3 5% 67%	4030
	11th to 20th	Day	3 3 1 3 2 2 2 2 3 5% 74%	4377
	21st to end	Day	6% 3 1 4 3 2 3 3 4 5% 67%	4813
June	1st to 10th	Day	5% 3 1 5% 4 3 4 3 5% 7% 59%	2660
	11th to 20th	Day	2 3 1 3 2 2 2 2 4 5% 74%	2660
	21st to end	Day	2 1 1 1 1 2 2 3 4 82%	2660
July	1st to 10th	Day	1 1 1 1 2 2 91%	4420
	11th to 20th	Day	1 1 2 1 1 2 2 3 3 84%	4420
	21st to end	Day	1 1 1 1 1 1 1 2 3 87%	4608
August	1st to 10th	Day	2 2 1 3 2 2 2 2 3 5% 76%	4091
	11th to 20th	Day	1 1 1 1 1 2 3 89%	3811
	21st to end	Day	1 1 1 1 1 1 1 1 2 2 88%	4180
September	1st to 10th	Day	2 1 1 1 1 2 2 2 4 85%	2280
	11th to 20th	Day	2 2 1 3 2 3 3 2 4 5% 73%	2280
	21st to end	Day	3 2 1 2 1 2 2 2 3 6% 76%	2054
October	1st to 10th	Day	5% 3 1 3 2 3 3 2 3 4 71%	1900
	11th to 20th	Day	5% 3 2 4 2 3 2 3 4 6% 67%	1900
	21st to end	Day	5% 3 1 4 3 2 3 3 4 7% 65%	2085
November	1st to 10th	Day	9% 6% 2 4 4 4 3 4 6% 7% 51%	1683
	11th to 20th	Day	6% 7% 2 5% 4 4 5% 5% 5% 8% 48%	1710
	21st to end	Day	4 8% 2 5% 4 3 5% 3 5% 7% 53%	1544
December	1st to 10th	Day	9% 9% 3 7% 3 3 4 4 5% 7% 47%	1520
	11th to 20th	Day	15% 12% 4 8% 5% 4 5% 4 6% 7% 30%	1928
	21st to end	Day	8% 8% 2 7% 4 3 6% 5% 9% 10% 37%	2794
January	1st to 10th	Night	5% 13% 3 7% 5% 5% 5% 4 6% 7% 41%	4406
	11th to 20th	Night	9% 14% 3 8% 5% 4 4 4 6% 7% 35%	4292
	21st to end	Night	12% 18% 3 8% 5% 4 5% 3 5% 6% 31%	4521
February	1st to 10th	Night	6% 10% 2 6% 4 4 4 3 5% 7% 48%	2470
	11th to 20th	Night	6% 11% 2 5% 3 4 4 4 6% 7% 46%	2295
	21st to end	Night	6% 15% 3 6% 4 3 4 3 5% 6% 46%	1884
March	1st to 10th	Night	5% 27% 8% 9% 4 3 3 2 4 4 31%	3674
	11th to 20th	Night	5% 13% 2 5% 3 2 3 3 4 5% 55%	3490
	21st to end	Night	9% 20% 4 7% 5% 4 4 4 7% 7% 30%	3654
April	1st to 10th	Night	6% 11% 2 6% 5% 3 4 4 6% 6% 47%	1900
	11th to 20th	Night	6% 9% 2 6% 3 3 4 3 6% 6% 52%	1879
	21st to end	Night	6% 7% 2 4 3 3 3 2 5% 7% 58%	1900
May	1st to 10th	Night	6% 9% 1 4 2 3 3 2 3 5% 62%	2935
	11th to 20th	Night	3 2 1 3 3 2 3 2 3 5% 72%	2516
	21st to end	Night	5% 4 1 3 2 2 2 3 3 5% 70%	2762
June	1st to 10th	Night	6% 3 2 3 3 3 4 3 4 8% 60%	1520
	11th to 20th	Night	2 2 1 3 3 2 2 2 4 5% 74%	1520
	21st to end	Night	2 2 3 2 2 1 2 3 4 78%	1520
July	1st to 10th	Night	1 1 1 1 1 1 1 1 2 91%	2540
	11th to 20th	Night	2 1 1 2 1 1 1 2 2 3 84%	2540
	21st to end	Night	1 1 1 1 1 1 2 2 4 85%	2946
August	1st to 10th	Night	2 2 1 3 2 2 3 2 5% 6% 73%	2848
	11th to 20th	Night	1 1 1 1 1 1 1 2 3 89%	3033
	21st to end	Night	1 1 1 1 1 1 1 1 2 2 88%	3498
September	1st to 10th	Night	1 1 1 1 1 2 1 2 3 84%	1900
	11th to 20th	Night	3 2 1 2 2 2 2 2 3 5% 77%	1900
	21st to end	Night	2 2 1 2 1 2 3 2 2 5% 78%	2121
October	1st to 10th	Night	5% 2 1 3 3 2 3 2 3 3 72%	2280
	11th to 20th	Night	5% 2 1 3 2 3 3 3 4 6% 70%	2280
	21st to end	Night	6% 3 1 2 2 3 3 3 5% 6% 67%	2512
November	1st to 10th	Night	9% 7% 2 5% 4 3 4 4 5% 7% 51%	2430
	11th to 20th	Night	7% 6% 2 4 4 3 4 4 7% 9% 51%	2470
	21st to end	Night	5% 7% 1 5% 4 4 4 3 5% 7% 55%	2635
December	1st to 10th	Night	10% 9% 2 5% 4 3 3 3 5% 7% 48%	2660
	11th to 20th	Night	15% 13% 3 8% 4 4 4 4 5% 7% 33%	3276
	21st to end	Night	10% 12% 3 8% 5% 5% 5% 6% 9% 7% 31%	4862

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	48% 3 11% 27% 9% 1	2539
	11th to 20th	Day	54% 3 12% 19% 8% 5%	2671
	21st to end	Day	53% 3 10% 20% 12% 2	3146
February	1st to 10th	Day	41% 2 11% 23% 17% 6%	1710
	11th to 20th	Day	40% 2 9% 25% 19% 3	1781
	21st to end	Day	42% 3 11% 25% 15% 4	1570
March	1st to 10th	Day	61% 3 7% 15% 12% 2	3195
	11th to 20th	Day	32% 2 9% 31% 22% 3	3490
	21st to end	Day	52% 3 13% 22% 8% 2	3997
April	1st to 10th	Day	41% 3 13% 24% 16% 3	2280
	11th to 20th	Day	35% 2 12% 27% 19% 5%	2252
	21st to end	Day	31% 2 14% 29% 21% 4	2280
May	1st to 10th	Day	24% 1 8% 27% 31% 8%	4030
	11th to 20th	Day	17% 2 6% 20% 43% 13%	4380
	21st to end	Day	22% 2 7% 34% 31% 3	4814
June	1st to 10th	Day	26% 3 9% 25% 28% 9%	2660
	11th to 20th	Day	15% 2 6% 23% 36% 19%	2660
	21st to end	Day	9% 2 2 15% 38% 33%	2660
July	1st to 10th	Day	3 1 1 6% 15% 73%	4351
	11th to 20th	Day	9% 2 1 7% 18% 64%	4345
	21st to end	Day	6% 1 1 6% 28% 58%	4463
August	1st to 10th	Day	13% 1 1 8% 24% 52%	4076
	11th to 20th	Day	5% 1 7% 38% 48%	3849
	21st to end	Day	7% 1 1 14% 40% 38%	4179
September	1st to 10th	Day	7% 1 1 10% 31% 50%	2280
	11th to 20th	Day	15% 2 4 21% 34% 24%	2280
	21st to end	Day	13% 2 4 22% 34% 25%	2054
October	1st to 10th	Day	20% 2 5% 20% 31% 22%	1900
	11th to 20th	Day	21% 2 6% 21% 34% 16%	1900
	21st to end	Day	23% 2 8% 26% 25% 16%	2085
November	1st to 10th	Day	34% 2 9% 23% 22% 9%	1683
	11th to 20th	Day	34% 4 11% 26% 22% 4	1710
	21st to end	Day	32% 2 11% 24% 23% 8%	1544
December	1st to 10th	Day	39% 3 9% 24% 21% 3	1520
	11th to 20th	Day	53% 2 10% 20% 14% 1	1928
	21st to end	Day	39% 4 18% 26% 11% 2	2794
January	1st to 10th	Night	43% 3 18% 26% 10% 1	4406
	11th to 20th	Night	48% 4 15% 17% 11% 5%	4292
	21st to end	Night	55% 2 11% 16% 13% 2	4521
February	1st to 10th	Night	37% 3 10% 26% 18% 6%	2470
	11th to 20th	Night	38% 2 11% 26% 20% 2	2297
	21st to end	Night	41% 3 11% 25% 16% 5%	1884
March	1st to 10th	Night	59% 1 11% 16% 10% 2	3674
	11th to 20th	Night	33% 2 7% 30% 25% 2	3490
	21st to end	Night	54% 4 13% 21% 7% 1	3654
April	1st to 10th	Night	39% 4 15% 24% 15% 3	1900
	11th to 20th	Night	34% 4 14% 25% 17% 5%	1879
	21st to end	Night	27% 3 14% 35% 17% 3	1900
May	1st to 10th	Night	29% 2 10% 27% 27% 5%	2935
	11th to 20th	Night	18% 2 9% 21% 36% 14%	2516
	21st to end	Night	20% 2 11% 39% 23% 4	2762
June	1st to 10th	Night	25% 4 15% 26% 23% 8%	1520
	11th to 20th	Night	14% 2 10% 25% 35% 14%	1520
	21st to end	Night	13% 2 4 17% 33% 31%	1520
July	1st to 10th	Night	5% 1 1 6% 17% 70%	2500
	11th to 20th	Night	10% 1 1 8% 17% 63%	2492
	21st to end	Night	7% 1 1 7% 30% 55%	2854
August	1st to 10th	Night	14% 2 1 9% 26% 48%	2839
	11th to 20th	Night	5% 1 1 11% 41% 41%	3061
	21st to end	Night	8% 1 2 14% 38% 37%	3498
September	1st to 10th	Night	9% 2 1 9% 32% 47%	1900
	11th to 20th	Night	14% 1 5% 21% 36% 23%	1900
	21st to end	Night	13% 1 4 23% 34% 25%	2121
October	1st to 10th	Night	20% 1 6% 20% 30% 23%	2280
	11th to 20th	Night	19% 1 6% 24% 31% 19%	2280
	21st to end	Night	20% 1 10% 26% 28% 14%	2512
November	1st to 10th	Night	35% 3 10% 23% 20% 10%	2430
	11th to 20th	Night	30% 4 12% 28% 23% 4	2470
	21st to end	Night	31% 3 10% 26% 23% 8%	2635
December	1st to 10th	Night	37% 3 11% 22% 22% 6%	2660
	11th to 20th	Night	52% 3 7% 19% 18% 1	3276
	21st to end	Night	48% 3 14% 21% 12% 2	4862

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	30% 17% 18% 26% 9%	180
	11th to 20th	Day	25% 17% 22% 22% 14%	259
	21st to end	Day	22% 18% 24% 23% 13% 2	407
February	1st to 10th	Day	23% 18% 24% 24% 11% 1	370
	11th to 20th	Day	25% 19% 26% 22% 8%	416
	21st to end	Day	20% 20% 27% 24% 8%	382
March	1st to 10th	Day	30% 27% 23% 14% 4 2	460
	11th to 20th	Day	29% 18% 23% 17% 10% 3	460
	21st to end	Day	24% 24% 31% 14% 7%	506
April	1st to 10th	Day	20% 22% 31% 17% 8% 1	460
	11th to 20th	Day	25% 20% 24% 21% 8% 2	452
	21st to end	Day	14% 21% 28% 21% 12% 3	460
May	1st to 10th	Day	17% 23% 30% 19% 9% 2	463
	11th to 20th	Day	15% 16% 31% 22% 10% 7%	488
	21st to end	Day	12% 15% 28% 24% 16% 5%	529
June	1st to 10th	Day	12% 15% 28% 23% 13% 8%	490
	11th to 20th	Day	8% 20% 33% 22% 14% 3	490
	21st to end	Day	5% 14% 30% 27% 19% 5%	490
July	1st to 10th	Day	2 8% 40% 26% 16% 7%	486
	11th to 20th	Day	1 9% 38% 27% 18% 7%	484
	21st to end	Day	2 6% 36% 29% 18% 9%	531
August	1st to 10th	Day	5% 9% 32% 27% 18% 9%	487
	11th to 20th	Day	3 11% 29% 28% 20% 9%	477
	21st to end	Day	3 11% 29% 32% 20% 5%	539
September	1st to 10th	Day	4 11% 31% 29% 22% 3	490
	11th to 20th	Day	5% 14% 26% 31% 19% 4	490
	21st to end	Day	6% 12% 29% 33% 16% 4	490
October	1st to 10th	Day	6% 16% 27% 25% 20% 6%	490
	11th to 20th	Day	9% 13% 23% 29% 22% 4	490
	21st to end	Day	14% 15% 22% 28% 18% 3	534
November	1st to 10th	Day	15% 13% 18% 27% 23% 4	273
	11th to 20th	Day	11% 10% 24% 27% 23% 4	270
	21st to end	Day	11% 15% 22% 32% 17% 3	192
December	1st to 10th	Day	18% 12% 26% 26% 13% 5%	180
	11th to 20th	Day	20% 17% 20% 27% 13% 3	180
	21st to end	Day	26% 13% 20% 24% 17% 2	198
January	1st to 10th	Night	17% 11% 27% 32% 13% 1	760
	11th to 20th	Night	14% 10% 29% 38% 9%	760
	21st to end	Night	18% 10% 26% 32% 13%	836
February	1st to 10th	Night	16% 12% 24% 37% 11%	760
	11th to 20th	Night	15% 11% 22% 38% 14% 1	744
	21st to end	Night	18% 12% 23% 39% 8% 1	628
March	1st to 10th	Night	23% 15% 21% 28% 12% 2	760
	11th to 20th	Night	18% 10% 21% 30% 20% 1	760
	21st to end	Night	19% 16% 21% 29% 14%	836
April	1st to 10th	Night	13% 11% 23% 37% 14% 1	760
	11th to 20th	Night	15% 11% 19% 37% 16% 2	751
	21st to end	Night	12% 9% 18% 37% 22% 2	760
May	1st to 10th	Night	13% 9% 24% 32% 20% 2	619
	11th to 20th	Night	9% 6% 13% 41% 29% 2	374
	21st to end	Night	12% 5% 13% 32% 35% 3	411
June	1st to 10th	Night	7% 4 14% 36% 36% 3	380
	11th to 20th	Night	3 4 15% 43% 33% 2	380
	21st to end	Night	3 3 9% 42% 42% 1	380
July	1st to 10th	Night	1 4 45% 47% 2	370
	11th to 20th	Night	1 1 5% 46% 44% 2	368
	21st to end	Night	1 1 3 35% 56% 4	526
August	1st to 10th	Night	2 1 4 38% 50% 5%	567
	11th to 20th	Night	1 2 8% 43% 41% 5%	695
	21st to end	Night	1 2 6% 44% 44% 2	836
September	1st to 10th	Night	2 3 10% 45% 38% 3	760
	11th to 20th	Night	4 3 9% 41% 38% 6%	760
	21st to end	Night	4 3 13% 43% 33% 5%	760
October	1st to 10th	Night	6% 6% 15% 41% 29% 3	760
	11th to 20th	Night	8% 6% 13% 40% 31% 3	760
	21st to end	Night	9% 7% 18% 39% 24% 3	836
November	1st to 10th	Night	13% 9% 17% 36% 24% 1	748
	11th to 20th	Night	11% 8% 24% 41% 15% 1	760
	21st to end	Night	11% 8% 26% 37% 17% 1	760
December	1st to 10th	Night	18% 11% 22% 38% 11% 1	760
	11th to 20th	Night	21% 9% 22% 36% 11% 1	760
	21st to end	Night	21% 11% 27% 34% 8%	836

Page generated at 2024-10-30 10:19:23. Version ac07

Copyright © 2024 Attilla Danko.