Annapolis Royal
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Annapolis Royal 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	19% 12% 4 9% 5% 4 4 3 4 6% 30%	101640
	Night	19% 14% 5% 11% 6% 4 4 3 4 5% 24%	97435
Transparency	Day	55% 4 12% 19% 10% 1	105199
	Night	60% 5% 11% 16% 7% 1	101953
Seeing	Day	31% 19% 30% 15% 4 1	16745
	Night	30% 18% 28% 18% 5%	24449

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	16% 21% 7% 15% 10% 5% 4 2 2 4 14%	2207
	11th to 20th	Day	18% 17% 8% 25% 8% 6% 3 2 3 3 8%	2654
	21st to end	Day	17% 16% 7% 19% 11% 5% 3 2 3 4 13%	3124
February	1st to 10th	Day	18% 19% 8% 16% 11% 4 4 2 3 4 10%	1710
	11th to 20th	Day	17% 17% 5% 16% 13% 5% 4 2 3 3 15%	1663
	21st to end	Day	11% 17% 6% 11% 9% 5% 4 2 4 6% 25%	1494
March	1st to 10th	Day	23% 19% 6% 10% 7% 4 3 2 2 4 20%	3368
	11th to 20th	Day	16% 18% 6% 11% 6% 4 4 3 4 4 25%	3480
	21st to end	Day	28% 14% 5% 10% 5% 4 4 3 3 3 21%	3816
April	1st to 10th	Day	22% 16% 4 7% 5% 3 4 3 4 5% 28%	2207
	11th to 20th	Day	20% 12% 2 5% 4 2 4 2 5% 7% 38%	2413
	21st to end	Day	20% 13% 3 7% 4 3 3 3 5% 6% 34%	2470
May	1st to 10th	Day	20% 13% 3 7% 6% 4 4 4 5% 6% 27%	4106
	11th to 20th	Day	17% 8% 2 7% 6% 5% 4 3 6% 7% 34%	4329
	21st to end	Day	16% 8% 2 7% 4 4 4 3 6% 8% 37%	4836
June	1st to 10th	Day	23% 9% 2 6% 6% 4 4 4 5% 7% 31%	2759
	11th to 20th	Day	20% 7% 2 6% 4 4 4 4 5% 7% 37%	2850
	21st to end	Day	22% 9% 3 8% 5% 4 4 3 5% 6% 31%	2850
July	1st to 10th	Day	20% 8% 3 6% 5% 3 4 3 6% 7% 35%	4760
	11th to 20th	Day	23% 8% 2 5% 4 4 4 3 5% 8% 35%	4616
	21st to end	Day	15% 7% 2 6% 4 4 5% 5% 6% 9% 37%	4473
August	1st to 10th	Day	22% 10% 3 7% 4 4 4 3 5% 5% 31%	4105
	11th to 20th	Day	13% 6% 3 7% 4 4 5% 4 6% 7% 42%	4045
	21st to end	Day	11% 6% 2 4 3 3 4 3 4 7% 53%	4453
September	1st to 10th	Day	18% 6% 2 4 3 3 3 3 4 6% 48%	2280
	11th to 20th	Day	15% 7% 2 5% 3 4 3 3 3 6% 47%	2108
	21st to end	Day	18% 7% 2 7% 3 3 2 3 4 6% 45%	2090
October	1st to 10th	Day	19% 8% 2 5% 4 3 4 3 5% 7% 40%	1900
	11th to 20th	Day	20% 11% 3 7% 4 4 3 3 4 6% 35%	1900
	21st to end	Day	21% 13% 3 6% 5% 4 4 2 4 5% 31%	2049
November	1st to 10th	Day	21% 14% 3 8% 5% 4 4 3 4 7% 28%	1628
	11th to 20th	Day	18% 19% 7% 10% 5% 5% 4 2 4 7% 21%	1520
	21st to end	Day	19% 20% 8% 12% 6% 5% 3 2 4 5% 17%	1520
December	1st to 10th	Day	23% 24% 6% 13% 5% 4 2 2 4 3 13%	1520
	11th to 20th	Day	23% 19% 6% 16% 7% 5% 4 2 3 3 10%	1906
	21st to end	Day	23% 19% 11% 16% 6% 4 3 2 2 4 11%	2431
January	1st to 10th	Night	16% 19% 8% 21% 7% 5% 3 3 3 3 12%	4748
	11th to 20th	Night	16% 22% 7% 21% 7% 5% 3 2 3 4 10%	4301
	21st to end	Night	18% 14% 7% 19% 8% 6% 4 3 4 5% 10%	4532
February	1st to 10th	Night	18% 19% 8% 17% 8% 5% 4 3 3 3 11%	2470
	11th to 20th	Night	18% 18% 6% 15% 10% 6% 4 2 3 4 13%	2403
	21st to end	Night	12% 16% 6% 12% 9% 5% 5% 3 4 5% 22%	1960
March	1st to 10th	Night	21% 17% 6% 12% 8% 5% 2 3 2 4 19%	3471
	11th to 20th	Night	16% 18% 6% 13% 7% 6% 5% 3 4 5% 17%	3479
	21st to end	Night	27% 13% 7% 9% 5% 4 4 2 3 3 23%	3816
April	1st to 10th	Night	23% 16% 4 7% 5% 3 4 3 4 5% 26%	1971
	11th to 20th	Night	21% 13% 3 6% 4 4 4 3 6% 7% 29%	1716
	21st to end	Night	21% 13% 3 7% 5% 4 4 3 4 6% 31%	1710
May	1st to 10th	Night	19% 17% 4 8% 4 4 4 3 5% 6% 26%	2834
	11th to 20th	Night	18% 9% 2 7% 6% 4 5% 4 6% 8% 30%	2572
	21st to end	Night	15% 9% 3 9% 6% 5% 5% 4 6% 7% 30%	2749
June	1st to 10th	Night	25% 8% 3 6% 4 3 5% 4 7% 8% 28%	1436
	11th to 20th	Night	19% 8% 2 6% 4 4 4 5% 7% 7% 34%	1330
	21st to end	Night	20% 8% 3 10% 6% 6% 5% 5% 5% 8% 25%	1330
July	1st to 10th	Night	23% 10% 4 7% 4 4 5% 4 5% 7% 27%	2210
	11th to 20th	Night	24% 8% 2 6% 4 4 5% 5% 7% 7% 29%	2306
	21st to end	Night	14% 8% 3 7% 4 4 5% 4 6% 8% 37%	3077
August	1st to 10th	Night	24% 9% 3 7% 4 3 4 3 6% 7% 31%	2825
	11th to 20th	Night	16% 8% 3 7% 5% 5% 5% 4 6% 8% 31%	2782
	21st to end	Night	11% 7% 2 6% 4 4 4 4 5% 8% 46%	3202
September	1st to 10th	Night	15% 5% 2 6% 4 4 5% 4 6% 7% 43%	1900
	11th to 20th	Night	17% 7% 2 5% 3 4 3 3 6% 7% 43%	2069
	21st to end	Night	17% 7% 3 6% 4 4 4 4 5% 6% 39%	2090
October	1st to 10th	Night	19% 7% 3 6% 4 4 3 4 6% 6% 38%	2279
	11th to 20th	Night	17% 10% 3 7% 5% 4 3 3 6% 6% 36%	2280
	21st to end	Night	24% 14% 3 7% 4 4 3 3 4 4 29%	2546
November	1st to 10th	Night	21% 13% 3 7% 5% 4 4 3 5% 6% 29%	2550
	11th to 20th	Night	19% 21% 5% 10% 4 4 5% 3 4 5% 20%	2660
	21st to end	Night	19% 19% 7% 10% 5% 4 4 3 4 6% 20%	2660
December	1st to 10th	Night	24% 22% 7% 12% 5% 4 4 2 4 5% 11%	2660
	11th to 20th	Night	21% 20% 7% 17% 7% 4 3 2 3 3 12%	3293
	21st to end	Night	24% 21% 7% 13% 5% 3 3 2 2 3 17%	5218

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	77% 3 14% 5% 2	2208
	11th to 20th	Day	82% 4 6% 6% 2	2654
	21st to end	Day	73% 8% 10% 7% 2	3124
February	1st to 10th	Day	79% 4 8% 6% 3	1710
	11th to 20th	Day	75% 4 8% 9% 4	1671
	21st to end	Day	62% 5% 10% 15% 6% 1	1494
March	1st to 10th	Day	70% 3 7% 15% 4 1	3372
	11th to 20th	Day	63% 4 11% 15% 7% 1	3480
	21st to end	Day	71% 2 6% 12% 8% 1	3816
April	1st to 10th	Day	60% 3 8% 16% 12% 2	2207
	11th to 20th	Day	49% 3 9% 25% 13% 1	2413
	21st to end	Day	53% 2 10% 19% 13% 2	2470
May	1st to 10th	Day	57% 3 13% 20% 6% 1	4120
	11th to 20th	Day	49% 3 17% 21% 9% 1	4333
	21st to end	Day	45% 4 19% 18% 13%	4836
June	1st to 10th	Day	53% 4 11% 22% 10%	2759
	11th to 20th	Day	46% 4 13% 22% 13% 2	2850
	21st to end	Day	55% 5% 11% 18% 11% 1	2850
July	1st to 10th	Day	48% 4 13% 21% 12% 1	4685
	11th to 20th	Day	48% 5% 13% 25% 9%	4535
	21st to end	Day	43% 7% 15% 23% 11% 1	4330
August	1st to 10th	Day	56% 4 10% 19% 10%	4092
	11th to 20th	Day	42% 6% 17% 25% 11%	4084
	21st to end	Day	32% 4 15% 28% 20% 1	4453
September	1st to 10th	Day	39% 3 12% 29% 15% 2	2280
	11th to 20th	Day	39% 4 12% 26% 17% 2	2108
	21st to end	Day	43% 3 9% 27% 15% 2	2090
October	1st to 10th	Day	45% 5% 11% 28% 11%	3160
	11th to 20th	Day	47% 4 9% 28% 13%	3140
	21st to end	Day	46% 3 13% 23% 14% 1	3351
November	1st to 10th	Day	59% 4 11% 19% 7% 1	1628
	11th to 20th	Day	66% 4 10% 15% 5% 1	1520
	21st to end	Day	72% 4 10% 11% 2	1520
December	1st to 10th	Day	77% 4 8% 9% 2	1520
	11th to 20th	Day	80% 4 6% 7% 3	1905
	21st to end	Day	81% 2 11% 4 2	2431
January	1st to 10th	Night	77% 4 8% 9% 1	4748
	11th to 20th	Night	79% 4 8% 7% 3	4301
	21st to end	Night	75% 5% 9% 9% 2	4532
February	1st to 10th	Night	79% 4 6% 7% 4	2470
	11th to 20th	Night	77% 3 7% 9% 4	2406
	21st to end	Night	64% 5% 10% 14% 6% 1	1960
March	1st to 10th	Night	69% 6% 6% 12% 6% 1	3480
	11th to 20th	Night	68% 5% 9% 11% 6% 1	3480
	21st to end	Night	68% 3 7% 13% 7% 1	3816
April	1st to 10th	Night	61% 4 9% 14% 11% 3	1971
	11th to 20th	Night	54% 4 9% 20% 12% 1	1716
	21st to end	Night	56% 4 10% 17% 13% 1	1710
May	1st to 10th	Night	60% 3 12% 19% 6% 1	2840
	11th to 20th	Night	51% 4 17% 21% 6% 1	2573
	21st to end	Night	51% 6% 18% 19% 6%	2750
June	1st to 10th	Night	53% 5% 13% 21% 8% 1	1436
	11th to 20th	Night	46% 5% 14% 23% 10% 1	1330
	21st to end	Night	54% 8% 11% 15% 8% 3	1330
July	1st to 10th	Night	55% 5% 12% 16% 11%	2175
	11th to 20th	Night	51% 8% 16% 16% 9%	2264
	21st to end	Night	45% 6% 14% 22% 12% 1	2980
August	1st to 10th	Night	54% 4 13% 23% 7%	2813
	11th to 20th	Night	46% 7% 18% 22% 7%	2809
	21st to end	Night	35% 7% 15% 26% 16% 1	3201
September	1st to 10th	Night	39% 5% 11% 29% 14% 1	1900
	11th to 20th	Night	41% 4 11% 28% 16% 1	2069
	21st to end	Night	45% 4 9% 25% 15% 2	2090
October	1st to 10th	Night	47% 4 13% 24% 11% 1	3799
	11th to 20th	Night	43% 4 12% 25% 15%	3779
	21st to end	Night	49% 3 9% 25% 13%	4182
November	1st to 10th	Night	56% 6% 12% 18% 8%	2550
	11th to 20th	Night	66% 6% 9% 13% 6%	2660
	21st to end	Night	67% 5% 14% 11% 3	2660
December	1st to 10th	Night	77% 3 9% 9% 2	2660
	11th to 20th	Night	78% 4 6% 10% 2	3295
	21st to end	Night	75% 3 9% 11% 2	5218

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	45% 25% 22% 8%	180
	11th to 20th	Day	42% 26% 23% 7% 2	294
	21st to end	Day	28% 27% 33% 10% 1	407
February	1st to 10th	Day	35% 26% 27% 10% 1	370
	11th to 20th	Day	40% 28% 21% 8% 2	366
	21st to end	Day	33% 26% 27% 12% 1	346
March	1st to 10th	Day	37% 23% 31% 7% 2	460
	11th to 20th	Day	36% 27% 25% 9% 2	460
	21st to end	Day	37% 26% 23% 10% 3 1	506
April	1st to 10th	Day	43% 25% 22% 8% 2 1	460
	11th to 20th	Day	34% 26% 26% 11% 2	452
	21st to end	Day	35% 18% 28% 13% 5%	460
May	1st to 10th	Day	34% 22% 30% 11% 3	463
	11th to 20th	Day	26% 20% 29% 19% 5%	631
	21st to end	Day	30% 19% 30% 18% 3 1	735
June	1st to 10th	Day	35% 16% 25% 19% 4	680
	11th to 20th	Day	24% 16% 35% 19% 6% 1	680
	21st to end	Day	31% 13% 33% 16% 5% 1	680
July	1st to 10th	Day	23% 12% 38% 20% 7% 1	670
	11th to 20th	Day	22% 9% 38% 21% 8% 1	668
	21st to end	Day	21% 11% 41% 23% 4	538
August	1st to 10th	Day	19% 12% 42% 22% 5% 1	486
	11th to 20th	Day	21% 12% 35% 22% 10% 1	479
	21st to end	Day	18% 14% 31% 27% 8% 2	539
September	1st to 10th	Day	20% 14% 39% 21% 6% 1	490
	11th to 20th	Day	23% 16% 31% 20% 7% 3	490
	21st to end	Day	24% 17% 30% 20% 8% 2	490
October	1st to 10th	Day	27% 16% 25% 20% 9% 3	390
	11th to 20th	Day	31% 18% 29% 15% 5% 2	390
	21st to end	Day	34% 21% 28% 12% 4 1	429
November	1st to 10th	Day	33% 21% 29% 11% 4 1	378
	11th to 20th	Day	41% 22% 22% 12% 4	370
	21st to end	Day	39% 25% 25% 6% 3 1	370
December	1st to 10th	Day	40% 26% 23% 10% 1	370
	11th to 20th	Day	49% 26% 19% 6% 1	370
	21st to end	Day	42% 27% 24% 5% 1 1	198
January	1st to 10th	Night	38% 25% 23% 13% 1	850
	11th to 20th	Night	39% 24% 23% 11% 3	774
	21st to end	Night	31% 27% 28% 12% 3	836
February	1st to 10th	Night	36% 24% 27% 11% 2	760
	11th to 20th	Night	39% 24% 25% 10% 2	743
	21st to end	Night	27% 27% 27% 16% 2	628
March	1st to 10th	Night	33% 24% 28% 13% 1	760
	11th to 20th	Night	33% 22% 26% 17% 3	760
	21st to end	Night	31% 21% 27% 16% 4	836
April	1st to 10th	Night	39% 18% 26% 16% 2	641
	11th to 20th	Night	30% 21% 30% 17% 3	564
	21st to end	Night	33% 16% 27% 18% 6%	570
May	1st to 10th	Night	29% 15% 33% 18% 4 1	570
	11th to 20th	Night	28% 14% 29% 24% 5%	562
	21st to end	Night	21% 15% 39% 20% 4 1	616
June	1st to 10th	Night	30% 12% 31% 22% 5%	486
	11th to 20th	Night	23% 12% 32% 26% 6% 1	380
	21st to end	Night	23% 9% 39% 20% 9% 1	380
July	1st to 10th	Night	19% 9% 39% 26% 6%	370
	11th to 20th	Night	23% 7% 35% 23% 11%	425
	21st to end	Night	19% 8% 35% 33% 5%	623
August	1st to 10th	Night	19% 8% 35% 29% 8% 1	568
	11th to 20th	Night	20% 9% 30% 29% 10% 1	562
	21st to end	Night	19% 8% 33% 30% 10%	627
September	1st to 10th	Night	18% 11% 34% 27% 9% 1	570
	11th to 20th	Night	22% 10% 27% 28% 12% 1	739
	21st to end	Night	23% 12% 30% 23% 10% 1	760
October	1st to 10th	Night	23% 10% 27% 29% 10% 1	760
	11th to 20th	Night	24% 19% 28% 19% 8% 1	760
	21st to end	Night	37% 20% 22% 16% 4	836
November	1st to 10th	Night	33% 17% 26% 18% 5% 1	798
	11th to 20th	Night	35% 22% 21% 16% 6%	850
	21st to end	Night	36% 21% 24% 15% 3	850
December	1st to 10th	Night	41% 22% 24% 11% 2	850
	11th to 20th	Night	39% 27% 23% 9% 2	850
	21st to end	Night	41% 24% 21% 11% 2	935

Page generated at 2024-11-03 03:11:27. Version ac07

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