Canton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Canton clear sky chart from 2005-11-06 to 2024-11-05.

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% 7% 2 6% 5% 4 4 4 6% 7% 38%	101265
	Night	18% 7% 2 6% 4 4 4 3 5% 6% 40%	97776
Transparency	Day	43% 6% 11% 22% 15% 2	104801
	Night	43% 6% 12% 23% 15% 2	102317
Seeing	Day	23% 14% 31% 20% 9% 3	14984
	Night	22% 11% 32% 27% 8% 1	23997

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	14% 7% 2 5% 3 4 5% 3 5% 6% 45%	2517
	11th to 20th	Day	16% 9% 3 10% 5% 4 4 5% 4 6% 35%	2520
	21st to end	Day	21% 13% 4 7% 4 4 4 3 4 5% 32%	2836
February	1st to 10th	Day	17% 8% 2 7% 5% 5% 5% 4 6% 5% 36%	1762
	11th to 20th	Day	13% 7% 3 7% 5% 4 5% 4 6% 6% 40%	1848
	21st to end	Day	20% 10% 3 5% 5% 4 4 3 4 5% 38%	1570
March	1st to 10th	Day	25% 11% 3 8% 4 3 3 3 4 4 33%	3116
	11th to 20th	Day	11% 6% 2 6% 4 5% 5% 5% 7% 8% 40%	3251
	21st to end	Day	20% 7% 3 6% 5% 3 3 3 5% 6% 38%	4166
April	1st to 10th	Day	18% 9% 2 5% 5% 4 3 4 5% 6% 37%	2280
	11th to 20th	Day	17% 6% 2 6% 5% 3 4 4 6% 7% 40%	2254
	21st to end	Day	21% 6% 2 5% 4 4 4 4 5% 6% 39%	2391
May	1st to 10th	Day	26% 8% 3 6% 4 3 4 3 6% 7% 29%	4106
	11th to 20th	Day	22% 7% 3 7% 4 4 4 3 5% 6% 34%	4297
	21st to end	Day	14% 5% 2 5% 4 4 4 4 7% 8% 44%	4837
June	1st to 10th	Day	17% 6% 2 6% 5% 5% 5% 5% 7% 8% 35%	2660
	11th to 20th	Day	16% 6% 2 6% 4 4 5% 4 7% 10% 36%	2660
	21st to end	Day	14% 7% 3 7% 4 4 5% 5% 6% 8% 37%	2660
July	1st to 10th	Day	11% 6% 3 7% 5% 6% 6% 4 6% 9% 36%	4440
	11th to 20th	Day	12% 5% 2 6% 5% 5% 5% 4 7% 10% 39%	4440
	21st to end	Day	16% 8% 3 7% 5% 5% 5% 4 6% 7% 34%	4814
August	1st to 10th	Day	18% 6% 2 8% 6% 5% 5% 4 6% 8% 31%	4277
	11th to 20th	Day	12% 6% 2 7% 5% 5% 5% 4 6% 8% 41%	3768
	21st to end	Day	9% 5% 2 6% 5% 5% 5% 4 7% 9% 42%	4180
September	1st to 10th	Day	12% 6% 2 7% 5% 4 5% 4 5% 6% 44%	2280
	11th to 20th	Day	13% 5% 2 5% 3 3 4 3 5% 6% 51%	2151
	21st to end	Day	18% 6% 2 5% 4 4 4 3 5% 7% 42%	2090
October	1st to 10th	Day	22% 6% 2 5% 3 3 5% 3 4 5% 40%	2055
	11th to 20th	Day	14% 6% 2 5% 4 4 4 3 6% 8% 45%	1879
	21st to end	Day	22% 6% 2 4 4 4 4 4 4 7% 40%	1881
November	1st to 10th	Day	13% 6% 2 6% 5% 3 4 3 4 5% 49%	1708
	11th to 20th	Day	20% 6% 2 4 2 3 4 3 5% 7% 45%	1710
	21st to end	Day	17% 8% 2 5% 4 3 3 3 4 6% 43%	1663
December	1st to 10th	Day	18% 6% 3 8% 4 5% 5% 4 5% 5% 37%	1520
	11th to 20th	Day	23% 5% 2 4 3 2 3 4 4 6% 44%	1906
	21st to end	Day	18% 13% 3 8% 5% 5% 4 4 4 6% 30%	2772
January	1st to 10th	Night	17% 7% 2 5% 4 3 3 3 6% 5% 46%	4429
	11th to 20th	Night	16% 8% 3 8% 4 3 3 4 5% 5% 41%	4440
	21st to end	Night	23% 12% 3 7% 5% 4 3 3 4 5% 31%	4819
February	1st to 10th	Night	16% 9% 3 5% 4 4 3 4 5% 6% 40%	2416
	11th to 20th	Night	14% 8% 3 7% 5% 4 5% 3 5% 6% 40%	2218
	21st to end	Night	18% 7% 2 6% 5% 4 4 3 4 6% 41%	1884
March	1st to 10th	Night	25% 11% 2 5% 4 4 3 3 4 5% 34%	3724
	11th to 20th	Night	12% 7% 3 6% 4 5% 5% 3 5% 7% 42%	3690
	21st to end	Night	22% 9% 2 6% 3 3 4 3 5% 5% 39%	3466
April	1st to 10th	Night	18% 8% 3 5% 5% 5% 4 4 5% 5% 38%	1900
	11th to 20th	Night	19% 6% 2 6% 5% 4 5% 3 4 6% 40%	1875
	21st to end	Night	21% 8% 2 6% 4 3 3 2 5% 5% 42%	1787
May	1st to 10th	Night	24% 10% 3 7% 5% 4 4 3 4 7% 29%	2834
	11th to 20th	Night	21% 9% 3 8% 4 4 4 5% 5% 6% 31%	2624
	21st to end	Night	17% 6% 2 4 3 4 4 4 6% 8% 43%	2738
June	1st to 10th	Night	17% 6% 2 6% 3 4 4 3 5% 7% 42%	1520
	11th to 20th	Night	17% 7% 2 5% 4 4 4 4 5% 9% 39%	1520
	21st to end	Night	15% 6% 2 6% 4 4 4 3 6% 9% 43%	1520
July	1st to 10th	Night	12% 5% 2 7% 4 5% 5% 5% 7% 10% 38%	2520
	11th to 20th	Night	15% 6% 2 6% 4 4 4 3 6% 10% 39%	2520
	21st to end	Night	17% 10% 3 7% 4 4 4 4 5% 7% 34%	2739
August	1st to 10th	Night	20% 6% 2 8% 4 5% 5% 4 6% 7% 31%	2620
	11th to 20th	Night	15% 7% 3 7% 4 4 4 3 6% 6% 41%	3057
	21st to end	Night	10% 5% 1 5% 3 3 4 3 5% 8% 53%	3476
September	1st to 10th	Night	14% 5% 2 7% 4 4 4 3 5% 6% 46%	1900
	11th to 20th	Night	14% 5% 2 5% 3 2 3 3 4 6% 53%	2028
	21st to end	Night	17% 6% 1 6% 4 3 4 4 5% 6% 45%	2090
October	1st to 10th	Night	20% 6% 2 6% 4 4 3 3 5% 6% 42%	2122
	11th to 20th	Night	15% 5% 2 5% 3 4 4 3 5% 6% 48%	2299
	21st to end	Night	24% 5% 2 4 4 4 4 3 4 6% 40%	2717
November	1st to 10th	Night	14% 5% 3 6% 4 4 4 4 5% 6% 48%	2470
	11th to 20th	Night	19% 7% 2 5% 3 3 4 3 5% 5% 45%	2470
	21st to end	Night	16% 6% 2 5% 4 4 5% 3 5% 6% 45%	2512
December	1st to 10th	Night	18% 7% 2 6% 4 4 4 3 5% 6% 39%	2660
	11th to 20th	Night	20% 6% 2 5% 3 4 4 4 5% 5% 41%	3288
	21st to end	Night	22% 10% 3 7% 4 4 4 3 4 5% 35%	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	39% 4 11% 33% 11% 2	2518
	11th to 20th	Day	49% 6% 10% 24% 10% 1	2520
	21st to end	Day	54% 5% 8% 21% 10% 1	2836
February	1st to 10th	Day	48% 6% 12% 20% 13% 2	1762
	11th to 20th	Day	43% 6% 9% 23% 16% 3	1857
	21st to end	Day	48% 4 10% 21% 14% 3	1570
March	1st to 10th	Day	55% 3 11% 18% 11% 2	3119
	11th to 20th	Day	36% 9% 12% 30% 12% 2	3251
	21st to end	Day	46% 4 6% 18% 21% 6%	4166
April	1st to 10th	Day	46% 5% 10% 20% 15% 4	2280
	11th to 20th	Day	43% 4 10% 22% 18% 3	2254
	21st to end	Day	45% 5% 9% 20% 17% 4	2391
May	1st to 10th	Day	52% 7% 12% 16% 12% 1	4120
	11th to 20th	Day	51% 6% 12% 19% 10% 1	4301
	21st to end	Day	36% 6% 11% 26% 18% 2	4837
June	1st to 10th	Day	44% 7% 11% 23% 13% 1	2660
	11th to 20th	Day	42% 6% 14% 24% 13% 2	2660
	21st to end	Day	42% 7% 12% 23% 15% 1	2660
July	1st to 10th	Day	43% 7% 12% 20% 16% 1	4370
	11th to 20th	Day	39% 7% 15% 24% 14% 2	4365
	21st to end	Day	48% 6% 11% 18% 15% 1	4661
August	1st to 10th	Day	49% 7% 14% 20% 9%	4263
	11th to 20th	Day	39% 7% 14% 28% 11% 1	3805
	21st to end	Day	34% 7% 13% 27% 16% 2	4180
September	1st to 10th	Day	40% 5% 10% 24% 19% 2	2280
	11th to 20th	Day	34% 4 9% 26% 24% 3	2151
	21st to end	Day	43% 4 9% 23% 19% 3	2090
October	1st to 10th	Day	38% 6% 9% 19% 25% 4	3419
	11th to 20th	Day	28% 4 9% 27% 28% 4	3095
	21st to end	Day	32% 5% 13% 25% 21% 4	3081
November	1st to 10th	Day	39% 4 11% 24% 19% 3	1708
	11th to 20th	Day	40% 4 10% 23% 20% 3	1710
	21st to end	Day	42% 4 12% 27% 12% 3	1663
December	1st to 10th	Day	48% 5% 13% 18% 15% 1	1520
	11th to 20th	Day	42% 4 16% 20% 16% 2	1906
	21st to end	Day	53% 6% 10% 20% 10% 1	2772
January	1st to 10th	Night	40% 4 12% 30% 11% 4	4429
	11th to 20th	Night	45% 5% 11% 24% 12% 4	4440
	21st to end	Night	55% 5% 9% 19% 11% 1	4819
February	1st to 10th	Night	46% 4 12% 23% 12% 2	2416
	11th to 20th	Night	44% 6% 9% 20% 18% 4	2220
	21st to end	Night	45% 4 9% 24% 13% 5%	1884
March	1st to 10th	Night	53% 5% 9% 19% 12% 2	3734
	11th to 20th	Night	39% 8% 14% 24% 14% 2	3691
	21st to end	Night	46% 5% 6% 13% 24% 5%	3466
April	1st to 10th	Night	46% 5% 9% 21% 15% 3	1900
	11th to 20th	Night	45% 6% 9% 19% 20% 1	1875
	21st to end	Night	45% 4 9% 22% 15% 5%	1787
May	1st to 10th	Night	55% 8% 11% 15% 10% 2	2840
	11th to 20th	Night	52% 7% 13% 15% 9% 2	2625
	21st to end	Night	39% 8% 15% 24% 14% 1	2739
June	1st to 10th	Night	43% 6% 11% 24% 15% 1	1520
	11th to 20th	Night	41% 6% 16% 25% 12% 1	1520
	21st to end	Night	37% 7% 15% 25% 15%	1520
July	1st to 10th	Night	40% 9% 16% 19% 15% 1	2480
	11th to 20th	Night	41% 7% 15% 24% 11% 1	2472
	21st to end	Night	49% 6% 12% 16% 15% 2	2651
August	1st to 10th	Night	50% 9% 13% 17% 9% 1	2610
	11th to 20th	Night	42% 6% 14% 29% 9%	3086
	21st to end	Night	28% 6% 14% 34% 17% 1	3476
September	1st to 10th	Night	40% 5% 10% 26% 18% 1	1900
	11th to 20th	Night	34% 5% 10% 24% 25% 2	2028
	21st to end	Night	40% 5% 9% 24% 20% 2	2090
October	1st to 10th	Night	38% 6% 13% 21% 19% 2	3538
	11th to 20th	Night	27% 4 10% 27% 29% 3	3810
	21st to end	Night	33% 4 13% 30% 19% 2	4467
November	1st to 10th	Night	38% 5% 11% 22% 20% 4	2470
	11th to 20th	Night	42% 4 11% 22% 19% 3	2470
	21st to end	Night	41% 4 14% 28% 12% 1	2512
December	1st to 10th	Night	45% 5% 13% 22% 14% 1	2660
	11th to 20th	Night	43% 5% 14% 18% 17% 2	3288
	21st to end	Night	52% 4 9% 23% 11% 1	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	27% 16% 34% 17% 6%	180
	11th to 20th	Day	31% 22% 33% 11% 3	180
	21st to end	Day	22% 23% 34% 13% 6% 1	216
February	1st to 10th	Day	32% 18% 34% 14% 2	322
	11th to 20th	Day	30% 21% 35% 13% 2	456
	21st to end	Day	31% 15% 35% 14% 4	382
March	1st to 10th	Day	25% 20% 36% 17% 3	460
	11th to 20th	Day	27% 20% 34% 15% 3 1	460
	21st to end	Day	31% 19% 33% 10% 5% 2	506
April	1st to 10th	Day	30% 18% 31% 12% 7% 2	460
	11th to 20th	Day	29% 18% 31% 14% 6% 1	452
	21st to end	Day	33% 14% 32% 13% 5% 2	460
May	1st to 10th	Day	35% 17% 26% 13% 8% 2	463
	11th to 20th	Day	22% 15% 35% 20% 6% 1	487
	21st to end	Day	21% 14% 29% 24% 9% 3	529
June	1st to 10th	Day	20% 13% 31% 24% 10% 3	490
	11th to 20th	Day	19% 12% 34% 24% 8% 2	490
	21st to end	Day	19% 11% 31% 27% 9% 3	490
July	1st to 10th	Day	15% 7% 30% 28% 15% 4	485
	11th to 20th	Day	13% 5% 32% 31% 15% 4	484
	21st to end	Day	15% 10% 34% 28% 10% 3	532
August	1st to 10th	Day	14% 8% 31% 30% 11% 5%	486
	11th to 20th	Day	15% 6% 31% 27% 14% 7%	479
	21st to end	Day	14% 8% 30% 26% 16% 7%	539
September	1st to 10th	Day	17% 11% 23% 25% 16% 8%	490
	11th to 20th	Day	16% 9% 27% 24% 13% 11%	490
	21st to end	Day	21% 11% 31% 22% 10% 6%	490
October	1st to 10th	Day	28% 9% 25% 19% 13% 6%	490
	11th to 20th	Day	19% 15% 30% 24% 9% 3	478
	21st to end	Day	30% 13% 25% 23% 8% 1	429
November	1st to 10th	Day	21% 13% 29% 25% 10% 2	378
	11th to 20th	Day	29% 17% 27% 18% 7% 1	370
	21st to end	Day	28% 13% 30% 20% 8% 1	323
December	1st to 10th	Day	23% 19% 35% 16% 7% 1	180
	11th to 20th	Day	31% 21% 35% 9% 4	180
	21st to end	Day	29% 14% 38% 12% 7% 1	198
January	1st to 10th	Night	23% 14% 38% 22% 3	760
	11th to 20th	Night	27% 15% 33% 23% 3	760
	21st to end	Night	22% 16% 36% 23% 3	836
February	1st to 10th	Night	23% 15% 34% 26% 2	760
	11th to 20th	Night	22% 17% 40% 19% 1	743
	21st to end	Night	27% 13% 36% 21% 3	628
March	1st to 10th	Night	25% 17% 36% 20% 3	760
	11th to 20th	Night	22% 17% 37% 20% 4	760
	21st to end	Night	25% 16% 34% 20% 4	836
April	1st to 10th	Night	25% 15% 35% 20% 4	760
	11th to 20th	Night	25% 15% 35% 20% 6%	751
	21st to end	Night	25% 17% 33% 20% 4	647
May	1st to 10th	Night	29% 15% 30% 22% 5%	570
	11th to 20th	Night	24% 12% 39% 22% 4	451
	21st to end	Night	20% 8% 30% 34% 8% 1	411
June	1st to 10th	Night	21% 6% 32% 31% 10%	380
	11th to 20th	Night	19% 6% 30% 35% 9%	380
	21st to end	Night	18% 4 32% 34% 11%	380
July	1st to 10th	Night	14% 5% 26% 38% 17% 1	370
	11th to 20th	Night	17% 3 22% 41% 16% 1	368
	21st to end	Night	14% 4 24% 43% 14%	416
August	1st to 10th	Night	13% 3 27% 42% 14% 1	440
	11th to 20th	Night	14% 5% 22% 38% 20% 1	722
	21st to end	Night	15% 4 23% 36% 20% 2	836
September	1st to 10th	Night	17% 5% 28% 33% 15% 2	760
	11th to 20th	Night	17% 4 25% 33% 17% 3	760
	21st to end	Night	21% 6% 27% 29% 15% 2	760
October	1st to 10th	Night	24% 7% 25% 30% 12% 3	760
	11th to 20th	Night	19% 10% 31% 30% 9% 1	760
	21st to end	Night	28% 10% 30% 24% 7%	836
November	1st to 10th	Night	18% 12% 31% 27% 10% 1	760
	11th to 20th	Night	24% 12% 33% 24% 6% 1	760
	21st to end	Night	24% 13% 31% 26% 5% 1	760
December	1st to 10th	Night	26% 13% 32% 23% 5% 1	760
	11th to 20th	Night	23% 14% 34% 25% 4	760
	21st to end	Night	28% 13% 32% 24% 2	836

Page generated at 2024-11-03 02:11:29. Version ac07

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