Sandy Cove
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sandy Cove clear sky chart from 2005-11-06 to 2026-08-15.

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	16% 12% 4 9% 5% 4 4 3 5% 6% 31%	144756
	Night	16% 14% 5% 10% 5% 4 4 3 4 6% 28%	137164
Transparency	Day	56% 2 10% 21% 10% 1	148329
	Night	59% 2 9% 19% 10% 1	141680
Seeing	Day	26% 15% 31% 19% 8% 2	17263
	Night	25% 12% 29% 25% 9% 1	26107

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% 17% 8% 14% 7% 5% 4 3 4 5% 19%	4094
	11th to 20th	Day	10% 24% 9% 20% 6% 6% 4 3 3 3 11%	4800
	21st to end	Day	10% 18% 8% 19% 8% 6% 4 3 3 3 17%	5780
February	1st to 10th	Day	13% 19% 8% 16% 7% 5% 4 3 4 4 19%	1890
	11th to 20th	Day	13% 18% 8% 14% 6% 5% 4 3 4 5% 21%	1843
	21st to end	Day	15% 20% 7% 13% 7% 5% 4 3 4 4 19%	1560
March	1st to 10th	Day	19% 16% 4 11% 5% 5% 3 3 4 5% 24%	5042
	11th to 20th	Day	13% 15% 6% 11% 6% 5% 5% 4 6% 7% 25%	5090
	21st to end	Day	17% 18% 6% 8% 4 4 3 3 3 4 30%	5586
April	1st to 10th	Day	20% 16% 5% 8% 4 3 4 4 4 6% 27%	2501
	11th to 20th	Day	23% 13% 3 5% 4 4 3 3 4 5% 33%	2612
	21st to end	Day	22% 13% 4 7% 4 3 3 2 4 5% 33%	2730
May	1st to 10th	Day	17% 11% 3 8% 5% 5% 5% 4 5% 7% 30%	7855
	11th to 20th	Day	17% 10% 3 7% 4 4 4 3 5% 7% 36%	8221
	21st to end	Day	21% 8% 3 6% 4 4 3 3 5% 6% 38%	9060
June	1st to 10th	Day	21% 8% 3 6% 5% 4 4 3 5% 7% 32%	2983
	11th to 20th	Day	16% 7% 3 7% 5% 5% 5% 4 5% 8% 36%	3150
	21st to end	Day	20% 8% 2 7% 5% 4 5% 4 6% 7% 32%	3150
July	1st to 10th	Day	16% 6% 2 7% 4 4 5% 4 6% 9% 36%	8879
	11th to 20th	Day	12% 5% 2 5% 4 4 4 4 6% 8% 47%	8544
	21st to end	Day	11% 6% 2 6% 4 4 4 4 6% 8% 44%	8762
August	1st to 10th	Day	14% 7% 3 7% 5% 5% 6% 4 6% 8% 34%	4364
	11th to 20th	Day	18% 7% 3 7% 4 4 4 5% 6% 8% 33%	4226
	21st to end	Day	10% 5% 2 6% 5% 5% 5% 4 6% 8% 43%	4527
September	1st to 10th	Day	16% 7% 2 7% 4 4 4 4 6% 7% 38%	2400
	11th to 20th	Day	16% 7% 2 5% 4 3 4 4 4 6% 44%	2305
	21st to end	Day	23% 9% 3 6% 4 4 5% 3 4 5% 33%	2147
October	1st to 10th	Day	20% 9% 2 8% 4 3 5% 3 5% 6% 34%	2000
	11th to 20th	Day	26% 14% 4 9% 5% 4 4 3 4 5% 24%	2000
	21st to end	Day	31% 15% 6% 8% 4 3 3 2 3 4 20%	2200
November	1st to 10th	Day	20% 17% 4 9% 4 4 4 3 4 6% 24%	1661
	11th to 20th	Day	19% 19% 7% 10% 5% 5% 4 2 4 4 21%	1680
	21st to end	Day	23% 23% 7% 11% 5% 4 3 3 3 4 13%	1680
December	1st to 10th	Day	16% 25% 8% 14% 6% 5% 4 3 4 4 11%	2680
	11th to 20th	Day	18% 23% 6% 13% 6% 4 2 2 3 3 19%	3066
	21st to end	Day	20% 24% 8% 14% 4 3 3 2 3 4 15%	3688
January	1st to 10th	Night	12% 19% 10% 16% 8% 6% 5% 3 4 4 15%	8815
	11th to 20th	Night	10% 22% 9% 22% 8% 5% 3 2 3 4 13%	8078
	21st to end	Night	9% 17% 10% 16% 8% 7% 5% 3 4 4 17%	8401
February	1st to 10th	Night	12% 18% 7% 13% 8% 5% 5% 4 4 6% 19%	2730
	11th to 20th	Night	12% 17% 8% 14% 7% 4 4 3 4 5% 23%	2663
	21st to end	Night	12% 20% 6% 13% 7% 6% 4 3 4 5% 20%	2241
March	1st to 10th	Night	16% 16% 5% 10% 5% 4 4 3 4 5% 29%	5018
	11th to 20th	Night	10% 16% 7% 10% 5% 5% 4 4 5% 7% 26%	5089
	21st to end	Night	21% 12% 5% 8% 5% 5% 3 3 4 4 30%	5588
April	1st to 10th	Night	21% 16% 4 6% 4 4 3 3 5% 6% 28%	2118
	11th to 20th	Night	18% 12% 3 6% 4 4 4 4 4 6% 34%	1976
	21st to end	Night	19% 11% 4 8% 6% 4 3 3 4 7% 31%	1890
May	1st to 10th	Night	16% 10% 3 6% 5% 5% 4 4 5% 8% 35%	5043
	11th to 20th	Night	17% 7% 2 6% 3 4 4 3 5% 7% 40%	4639
	21st to end	Night	17% 9% 2 6% 4 4 3 3 5% 8% 41%	5114
June	1st to 10th	Night	15% 10% 3 7% 4 5% 5% 4 5% 6% 37%	1631
	11th to 20th	Night	16% 5% 2 5% 5% 3 4 4 6% 8% 42%	1470
	21st to end	Night	15% 8% 3 7% 4 4 4 5% 7% 8% 36%	1470
July	1st to 10th	Night	13% 7% 3 6% 4 4 4 4 6% 8% 41%	4110
	11th to 20th	Night	14% 6% 2 5% 3 4 4 3 5% 7% 48%	4427
	21st to end	Night	13% 6% 2 5% 3 3 4 4 5% 7% 48%	5311
August	1st to 10th	Night	12% 6% 2 5% 4 4 4 4 6% 7% 45%	3005
	11th to 20th	Night	18% 7% 2 5% 4 4 4 3 5% 7% 43%	2911
	21st to end	Night	16% 5% 1 5% 3 4 3 3 5% 7% 49%	3337
September	1st to 10th	Night	14% 5% 3 5% 4 4 4 4 6% 7% 45%	2000
	11th to 20th	Night	14% 5% 2 4 4 3 4 4 5% 6% 49%	2092
	21st to end	Night	18% 8% 2 6% 3 4 4 3 4 7% 40%	2252
October	1st to 10th	Night	19% 9% 3 6% 4 4 5% 3 5% 6% 37%	2400
	11th to 20th	Night	24% 13% 3 8% 5% 4 5% 3 4 5% 26%	2400
	21st to end	Night	26% 17% 4 8% 4 4 3 2 3 4 23%	2640
November	1st to 10th	Night	23% 16% 3 7% 4 4 3 3 4 6% 28%	2854
	11th to 20th	Night	19% 16% 4 9% 6% 4 4 3 5% 6% 25%	2940
	21st to end	Night	22% 20% 6% 11% 6% 5% 3 2 4 5% 15%	2940
December	1st to 10th	Night	18% 25% 7% 14% 6% 4 5% 4 3 4 10%	4720
	11th to 20th	Night	17% 23% 7% 14% 6% 4 3 2 3 4 16%	5348
	21st to end	Night	21% 22% 7% 15% 5% 4 3 3 3 3 15%	7503

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	70% 1 6% 16% 6% 1	4095
	11th to 20th	Day	81% 1 4 7% 6% 1	4830
	21st to end	Day	75% 1 4 11% 8% 1	5780
February	1st to 10th	Day	71% 2 6% 14% 6% 1	1890
	11th to 20th	Day	66% 2 9% 13% 8% 1	1852
	21st to end	Day	70% 2 7% 14% 7%	1560
March	1st to 10th	Day	65% 2 10% 8% 14% 2	5045
	11th to 20th	Day	60% 2 14% 16% 7% 2	5090
	21st to end	Day	60% 2 7% 19% 11% 2	5586
April	1st to 10th	Day	60% 2 9% 18% 10% 2	2501
	11th to 20th	Day	56% 2 6% 23% 12% 1	2612
	21st to end	Day	56% 2 8% 18% 14% 3	2730
May	1st to 10th	Day	55% 2 8% 22% 9% 4	7864
	11th to 20th	Day	49% 2 8% 25% 14% 1	8225
	21st to end	Day	49% 2 10% 22% 15% 2	9061
June	1st to 10th	Day	52% 3 9% 22% 14%	2983
	11th to 20th	Day	47% 3 10% 25% 14% 1	3150
	21st to end	Day	51% 4 13% 21% 10% 1	3150
July	1st to 10th	Day	46% 3 15% 25% 11% 1	8806
	11th to 20th	Day	37% 2 13% 38% 11%	8464
	21st to end	Day	40% 2 14% 32% 12%	8567
August	1st to 10th	Day	48% 2 12% 28% 9% 1	4351
	11th to 20th	Day	49% 3 13% 27% 8%	4265
	21st to end	Day	40% 3 11% 35% 10%	4527
September	1st to 10th	Day	45% 4 13% 26% 11% 1	2400
	11th to 20th	Day	42% 2 13% 31% 12% 1	2305
	21st to end	Day	54% 4 9% 25% 8%	2147
October	1st to 10th	Day	53% 3 11% 24% 9% 1	3260
	11th to 20th	Day	56% 4 11% 23% 6%	3240
	21st to end	Day	68% 2 11% 15% 5%	3538
November	1st to 10th	Day	62% 3 12% 18% 5%	1661
	11th to 20th	Day	68% 3 10% 13% 5% 1	1680
	21st to end	Day	76% 3 8% 9% 3	1680
December	1st to 10th	Day	78% 2 9% 8% 2	2680
	11th to 20th	Day	73% 1 5% 13% 7%	3066
	21st to end	Day	76% 1 3 14% 6%	3688
January	1st to 10th	Night	76% 1 5% 13% 5%	8815
	11th to 20th	Night	80% 1 5% 7% 8%	8123
	21st to end	Night	74% 1 5% 10% 9% 1	8401
February	1st to 10th	Night	67% 3 8% 15% 7% 1	2730
	11th to 20th	Night	65% 2 8% 17% 7% 1	2665
	21st to end	Night	69% 2 8% 14% 6% 1	2241
March	1st to 10th	Night	60% 1 9% 13% 13% 4	5028
	11th to 20th	Night	59% 2 14% 16% 8% 1	5090
	21st to end	Night	60% 2 5% 20% 12% 2	5588
April	1st to 10th	Night	58% 3 8% 19% 10% 2	2118
	11th to 20th	Night	51% 3 7% 22% 14% 2	1976
	21st to end	Night	55% 4 7% 17% 15% 2	1890
May	1st to 10th	Night	50% 2 7% 27% 12% 3	5050
	11th to 20th	Night	44% 3 9% 25% 17% 2	4640
	21st to end	Night	44% 2 9% 28% 15% 1	5115
June	1st to 10th	Night	48% 4 11% 20% 14% 2	1631
	11th to 20th	Night	40% 3 11% 28% 18%	1470
	21st to end	Night	45% 4 16% 22% 12% 1	1470
July	1st to 10th	Night	43% 3 15% 29% 11% 1	4075
	11th to 20th	Night	38% 2 13% 36% 11% 1	4384
	21st to end	Night	37% 3 10% 36% 13%	5191
August	1st to 10th	Night	38% 3 17% 25% 15% 2	2994
	11th to 20th	Night	43% 3 19% 25% 10% 1	2938
	21st to end	Night	37% 3 12% 35% 12% 1	3337
September	1st to 10th	Night	37% 5% 16% 29% 12% 1	2000
	11th to 20th	Night	36% 3 16% 32% 13%	2092
	21st to end	Night	46% 3 12% 27% 11%	2252
October	1st to 10th	Night	43% 3 9% 30% 15%	3920
	11th to 20th	Night	55% 2 14% 21% 8%	3899
	21st to end	Night	62% 2 16% 14% 6%	4252
November	1st to 10th	Night	59% 3 12% 20% 6%	2854
	11th to 20th	Night	61% 4 12% 17% 6% 1	2940
	21st to end	Night	73% 3 9% 11% 4	2940
December	1st to 10th	Night	80% 2 8% 7% 2	4720
	11th to 20th	Night	74% 2 5% 10% 8%	5348
	21st to end	Night	77% 1 5% 11% 5%	7503

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	23% 25% 35% 13% 4 1	220
	11th to 20th	Day	27% 20% 33% 15% 4	247
	21st to end	Day	27% 17% 35% 16% 5%	363
February	1st to 10th	Day	28% 28% 32% 8% 3 1	330
	11th to 20th	Day	27% 26% 35% 11% 1	330
	21st to end	Day	35% 22% 34% 9%	275
March	1st to 10th	Day	27% 20% 37% 13% 3 1	540
	11th to 20th	Day	26% 22% 35% 13% 4 1	540
	21st to end	Day	32% 19% 28% 15% 4 1	594
April	1st to 10th	Day	31% 20% 30% 14% 5% 1	540
	11th to 20th	Day	39% 15% 23% 14% 6% 3	532
	21st to end	Day	33% 13% 34% 13% 6% 1	540
May	1st to 10th	Day	30% 13% 30% 17% 7% 2	543
	11th to 20th	Day	23% 16% 31% 16% 10% 3	567
	21st to end	Day	24% 18% 30% 17% 9% 2	617
June	1st to 10th	Day	24% 13% 31% 25% 6% 1	613
	11th to 20th	Day	21% 15% 32% 22% 8% 2	780
	21st to end	Day	25% 12% 33% 20% 8% 2	780
July	1st to 10th	Day	15% 10% 34% 30% 10% 1	771
	11th to 20th	Day	17% 13% 30% 27% 11% 3	654
	21st to end	Day	14% 10% 33% 29% 11% 3	620
August	1st to 10th	Day	18% 9% 28% 28% 13% 5%	566
	11th to 20th	Day	18% 7% 27% 26% 15% 8%	535
	21st to end	Day	18% 11% 30% 22% 14% 4	583
September	1st to 10th	Day	20% 10% 29% 23% 12% 6%	530
	11th to 20th	Day	17% 7% 24% 27% 17% 8%	530
	21st to end	Day	26% 10% 24% 24% 13% 3	530
October	1st to 10th	Day	26% 13% 25% 21% 12% 3	530
	11th to 20th	Day	30% 17% 33% 14% 4 2	530
	21st to end	Day	40% 14% 28% 16% 2 1	583
November	1st to 10th	Day	37% 18% 30% 14% 1	228
	11th to 20th	Day	30% 24% 34% 9% 4	220
	21st to end	Day	34% 17% 38% 8% 2 1	220
December	1st to 10th	Day	29% 18% 37% 14% 3	220
	11th to 20th	Day	40% 17% 30% 10% 2	220
	21st to end	Day	34% 21% 26% 17% 1 1	242
January	1st to 10th	Night	28% 16% 34% 17% 4	1047
	11th to 20th	Night	30% 17% 31% 17% 4	840
	21st to end	Night	21% 13% 35% 23% 7% 1	924
February	1st to 10th	Night	24% 18% 35% 19% 4	840
	11th to 20th	Night	23% 20% 32% 21% 5%	823
	21st to end	Night	25% 21% 28% 23% 3	692
March	1st to 10th	Night	23% 19% 35% 19% 4	840
	11th to 20th	Night	24% 17% 35% 19% 4 1	840
	21st to end	Night	25% 15% 29% 24% 7%	924
April	1st to 10th	Night	31% 13% 32% 20% 4	840
	11th to 20th	Night	27% 13% 27% 23% 9% 1	732
	21st to end	Night	26% 12% 28% 24% 10% 1	630
May	1st to 10th	Night	24% 7% 27% 31% 10% 1	557
	11th to 20th	Night	21% 8% 31% 32% 8%	414
	21st to end	Night	15% 10% 35% 33% 9%	455
June	1st to 10th	Night	17% 9% 32% 32% 10%	420
	11th to 20th	Night	18% 9% 24% 39% 10%	420
	21st to end	Night	19% 7% 26% 35% 12% 1	420
July	1st to 10th	Night	15% 3 26% 42% 14%	410
	11th to 20th	Night	14% 6% 26% 36% 18%	408
	21st to end	Night	13% 5% 23% 40% 18% 1	534
August	1st to 10th	Night	16% 3 17% 40% 21% 2	627
	11th to 20th	Night	16% 4 16% 41% 21% 2	606
	21st to end	Night	19% 6% 24% 30% 18% 3	722
September	1st to 10th	Night	16% 8% 25% 32% 17% 2	800
	11th to 20th	Night	16% 7% 24% 29% 21% 4	800
	21st to end	Night	24% 7% 22% 28% 16% 2	800
October	1st to 10th	Night	25% 10% 26% 26% 12% 1	800
	11th to 20th	Night	31% 11% 29% 21% 7% 1	800
	21st to end	Night	37% 13% 28% 19% 3	880
November	1st to 10th	Night	36% 10% 25% 22% 6% 1	820
	11th to 20th	Night	29% 17% 28% 20% 6%	840
	21st to end	Night	36% 14% 28% 18% 4	840
December	1st to 10th	Night	32% 16% 31% 16% 5%	840
	11th to 20th	Night	29% 18% 33% 15% 3 1	840
	21st to end	Night	35% 15% 29% 17% 3	1082

Page generated at 2026-08-12 03:37:14. Version ac07

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