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 2024-02-20.

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	18% 12% 5% 8% 6% 3 4 4 4 6% 29%	78375
	Night	17% 14% 5% 9% 6% 3 4 4 4 5% 27%	80788
Transparency	Day	57% 3 10% 19% 9% 1	78075
	Night	60% 3 10% 17% 9% 1	80623
Seeing	Day	25% 15% 30% 19% 8% 2	13929
	Night	25% 12% 28% 24% 9% 1	23082

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% 22% 13% 14% 5% 2 2 2 3 4 16%	2208
	11th to 20th	Day	12% 16% 10% 19% 10% 4 4 4 3 4 15%	2586
	21st to end	Day	17% 24% 9% 12% 6% 4 3 3 3 4 16%	3124
February	1st to 10th	Day	14% 18% 8% 15% 8% 3 5% 3 4 4 18%	1710
	11th to 20th	Day	14% 16% 8% 12% 7% 3 5% 3 4 5% 23%	1654
	21st to end	Day	16% 19% 8% 11% 8% 4 5% 3 4 4 20%	1333
March	1st to 10th	Day	15% 15% 5% 9% 7% 4 5% 4 3 7% 26%	1977
	11th to 20th	Day	13% 14% 6% 11% 7% 4 4 4 5% 5% 28%	1980
	21st to end	Day	18% 11% 4 7% 5% 2 3 4 4 5% 35%	2178
April	1st to 10th	Day	20% 15% 6% 7% 5% 2 4 4 4 6% 27%	2143
	11th to 20th	Day	21% 11% 4 5% 4 3 4 3 4 6% 34%	2234
	21st to end	Day	22% 12% 4 6% 5% 2 4 3 4 6% 33%	2340
May	1st to 10th	Day	20% 8% 3 6% 5% 4 5% 4 5% 8% 33%	2401
	11th to 20th	Day	19% 9% 3 6% 5% 3 4 5% 4 7% 35%	2478
	21st to end	Day	16% 6% 3 6% 5% 3 4 5% 5% 7% 40%	2725
June	1st to 10th	Day	21% 7% 3 6% 5% 3 4 4 5% 8% 33%	2556
	11th to 20th	Day	16% 6% 3 6% 5% 4 5% 5% 5% 8% 37%	2700
	21st to end	Day	20% 8% 3 6% 6% 3 5% 5% 5% 7% 32%	2700
July	1st to 10th	Day	14% 5% 2 6% 5% 3 5% 5% 5% 8% 41%	2700
	11th to 20th	Day	14% 6% 3 6% 6% 3 6% 5% 6% 7% 37%	2602
	21st to end	Day	14% 6% 3 6% 5% 4 5% 5% 6% 9% 36%	2678
August	1st to 10th	Day	15% 6% 3 6% 6% 4 5% 5% 6% 8% 36%	2327
	11th to 20th	Day	16% 6% 3 6% 7% 3 5% 6% 5% 8% 36%	2303
	21st to end	Day	15% 7% 2 6% 6% 4 6% 5% 6% 8% 35%	2500
September	1st to 10th	Day	16% 7% 2 6% 5% 3 4 5% 6% 7% 38%	2160
	11th to 20th	Day	18% 7% 3 5% 4 3 4 4 4 6% 41%	2075
	21st to end	Day	24% 8% 3 5% 5% 3 5% 5% 4 5% 33%	1933
October	1st to 10th	Day	22% 9% 3 7% 5% 3 5% 4 5% 6% 33%	1800
	11th to 20th	Day	28% 13% 4 8% 6% 3 4 3 4 5% 22%	1800
	21st to end	Day	33% 14% 6% 7% 5% 2 3 3 3 4 19%	1980
November	1st to 10th	Day	20% 15% 4 8% 6% 3 5% 3 4 7% 25%	1500
	11th to 20th	Day	20% 17% 7% 9% 6% 4 4 3 4 5% 21%	1520
	21st to end	Day	24% 21% 8% 10% 6% 3 3 4 3 4 14%	1520
December	1st to 10th	Day	18% 25% 8% 10% 6% 3 4 4 4 5% 14%	1520
	11th to 20th	Day	19% 23% 6% 10% 7% 3 4 3 3 4 18%	1906
	21st to end	Day	23% 23% 8% 12% 7% 2 3 2 2 3 14%	2524
January	1st to 10th	Night	16% 22% 10% 15% 7% 4 4 4 3 4 12%	4746
	11th to 20th	Night	12% 17% 7% 16% 13% 5% 5% 4 4 4 13%	4367
	21st to end	Night	16% 21% 10% 13% 7% 4 4 3 3 3 16%	4532
February	1st to 10th	Night	13% 18% 7% 12% 9% 4 5% 5% 4 6% 18%	2470
	11th to 20th	Night	12% 16% 8% 13% 8% 3 4 4 4 5% 25%	2397
	21st to end	Night	13% 19% 7% 11% 8% 4 4 4 4 5% 21%	1918
March	1st to 10th	Night	14% 13% 6% 9% 6% 4 4 4 4 5% 32%	1970
	11th to 20th	Night	14% 14% 6% 8% 6% 3 4 3 4 6% 31%	1979
	21st to end	Night	16% 11% 4 7% 6% 3 3 4 4 6% 37%	2178
April	1st to 10th	Night	22% 14% 5% 5% 5% 3 4 4 5% 6% 28%	1816
	11th to 20th	Night	18% 12% 5% 5% 4 3 4 5% 4 6% 36%	1691
	21st to end	Night	20% 11% 4 8% 6% 3 4 4 4 6% 31%	1620
May	1st to 10th	Night	18% 8% 3 5% 4 3 4 5% 5% 8% 37%	1558
	11th to 20th	Night	16% 6% 2 5% 5% 3 5% 4 6% 8% 40%	1415
	21st to end	Night	12% 7% 3 5% 4 3 4 5% 6% 9% 42%	1550
June	1st to 10th	Night	15% 9% 4 6% 5% 4 6% 4 5% 6% 36%	1399
	11th to 20th	Night	16% 5% 2 4 5% 2 4 5% 6% 8% 44%	1260
	21st to end	Night	15% 7% 3 6% 4 2 5% 5% 7% 8% 37%	1260
July	1st to 10th	Night	11% 6% 2 4 4 2 3 5% 6% 8% 49%	1260
	11th to 20th	Night	13% 6% 2 5% 5% 3 4 5% 5% 7% 45%	1356
	21st to end	Night	11% 5% 2 4 4 4 5% 7% 6% 8% 43%	1636
August	1st to 10th	Night	13% 5% 2 5% 5% 3 4 5% 5% 7% 45%	1611
	11th to 20th	Night	12% 6% 2 4 5% 3 5% 5% 6% 7% 44%	1598
	21st to end	Night	17% 6% 2 6% 5% 4 4 4 5% 7% 41%	1837
September	1st to 10th	Night	13% 5% 3 4 4 3 4 5% 6% 7% 45%	1800
	11th to 20th	Night	15% 6% 2 4 4 2 4 5% 5% 6% 46%	1882
	21st to end	Night	18% 7% 3 6% 4 3 4 4 5% 7% 40%	2026
October	1st to 10th	Night	20% 10% 3 6% 5% 3 4 4 5% 5% 36%	2160
	11th to 20th	Night	26% 12% 3 6% 6% 3 5% 4 4 6% 24%	2160
	21st to end	Night	28% 17% 4 7% 5% 3 3 3 3 4 22%	2376
November	1st to 10th	Night	23% 14% 3 6% 5% 3 3 3 4 6% 29%	2575
	11th to 20th	Night	20% 14% 5% 8% 7% 3 4 4 5% 6% 25%	2660
	21st to end	Night	23% 19% 6% 9% 7% 4 3 3 4 5% 16%	2660
December	1st to 10th	Night	20% 23% 9% 11% 7% 4 4 4 2 4 12%	2660
	11th to 20th	Night	19% 22% 8% 11% 7% 2 3 3 3 4 18%	3288
	21st to end	Night	23% 22% 8% 13% 8% 3 3 3 3 3 12%	5117

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	76% 2 9% 9% 5%	2209
	11th to 20th	Day	77% 2 6% 9% 5% 1	2586
	21st to end	Day	76% 2 6% 10% 6% 1	3124
February	1st to 10th	Day	72% 2 6% 14% 5% 1	1710
	11th to 20th	Day	65% 2 9% 13% 9% 2	1663
	21st to end	Day	70% 3 8% 13% 7%	1333
March	1st to 10th	Day	60% 3 12% 14% 10% 1	1980
	11th to 20th	Day	59% 3 10% 17% 10% 2	1980
	21st to end	Day	52% 3 8% 18% 14% 4	2178
April	1st to 10th	Day	59% 2 10% 17% 10% 2	2143
	11th to 20th	Day	54% 3 7% 24% 12% 1	2234
	21st to end	Day	56% 3 8% 17% 14% 3	2340
May	1st to 10th	Day	51% 4 8% 20% 13% 3	2401
	11th to 20th	Day	49% 4 9% 23% 14% 2	2482
	21st to end	Day	44% 4 13% 22% 13% 3	2725
June	1st to 10th	Day	51% 4 10% 22% 13% 1	2556
	11th to 20th	Day	45% 4 10% 25% 15% 1	2700
	21st to end	Day	50% 5% 13% 21% 10% 1	2700
July	1st to 10th	Day	40% 4 13% 28% 13% 1	2626
	11th to 20th	Day	43% 5% 12% 29% 11% 1	2522
	21st to end	Day	45% 5% 12% 29% 9%	2528
August	1st to 10th	Day	46% 4 14% 25% 10% 1	2314
	11th to 20th	Day	47% 4 15% 25% 8% 1	2303
	21st to end	Day	47% 5% 13% 24% 10%	2500
September	1st to 10th	Day	45% 4 12% 26% 12% 1	2160
	11th to 20th	Day	45% 3 14% 29% 9% 1	2075
	21st to end	Day	54% 4 10% 26% 6%	1933
October	1st to 10th	Day	53% 5% 11% 20% 10% 1	1800
	11th to 20th	Day	67% 3 11% 14% 5% 1	1800
	21st to end	Day	70% 2 9% 13% 6%	1980
November	1st to 10th	Day	61% 3 13% 18% 5%	1500
	11th to 20th	Day	67% 4 10% 12% 5% 1	1520
	21st to end	Day	75% 3 8% 10% 3 1	1520
December	1st to 10th	Day	74% 4 9% 10% 3 1	1520
	11th to 20th	Day	73% 2 6% 12% 6%	1906
	21st to end	Day	79% 1 4 13% 3	2524
January	1st to 10th	Night	79% 2 7% 10% 3	4746
	11th to 20th	Night	77% 2 8% 9% 4 1	4367
	21st to end	Night	76% 2 6% 9% 6% 1	4532
February	1st to 10th	Night	69% 3 8% 14% 6% 1	2470
	11th to 20th	Night	63% 2 9% 17% 8% 1	2399
	21st to end	Night	68% 3 9% 14% 6% 1	1918
March	1st to 10th	Night	56% 2 12% 15% 13% 2	1980
	11th to 20th	Night	56% 3 11% 18% 11% 2	1980
	21st to end	Night	50% 3 8% 21% 15% 3	2178
April	1st to 10th	Night	57% 4 7% 19% 11% 2	1816
	11th to 20th	Night	50% 3 7% 22% 15% 2	1691
	21st to end	Night	55% 5% 7% 15% 15% 3	1620
May	1st to 10th	Night	46% 4 9% 23% 15% 3	1558
	11th to 20th	Night	43% 4 8% 24% 19% 2	1416
	21st to end	Night	38% 5% 15% 23% 16% 3	1551
June	1st to 10th	Night	48% 5% 12% 21% 12% 3	1399
	11th to 20th	Night	38% 4 11% 28% 19%	1260
	21st to end	Night	43% 5% 17% 22% 12% 1	1260
July	1st to 10th	Night	32% 4 14% 29% 19% 2	1225
	11th to 20th	Night	39% 4 13% 30% 12% 2	1313
	21st to end	Night	38% 6% 15% 28% 12% 1	1545
August	1st to 10th	Night	37% 5% 17% 26% 13% 1	1600
	11th to 20th	Night	37% 5% 20% 26% 11% 1	1598
	21st to end	Night	43% 4 14% 27% 10% 1	1837
September	1st to 10th	Night	37% 6% 15% 28% 13% 1	1800
	11th to 20th	Night	38% 4 16% 32% 10%	1882
	21st to end	Night	46% 3 13% 29% 9%	2026
October	1st to 10th	Night	51% 4 11% 20% 13%	2160
	11th to 20th	Night	62% 4 11% 17% 5%	2160
	21st to end	Night	68% 3 9% 13% 7%	2376
November	1st to 10th	Night	58% 3 13% 20% 6%	2575
	11th to 20th	Night	61% 4 12% 16% 6% 1	2660
	21st to end	Night	72% 4 10% 11% 4	2660
December	1st to 10th	Night	78% 4 5% 9% 3	2660
	11th to 20th	Night	73% 3 6% 12% 5% 1	3288
	21st to end	Night	80% 2 6% 10% 3	5117

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	24% 26% 31% 14% 4 1	180
	11th to 20th	Day	26% 19% 33% 16% 4	201
	21st to end	Day	28% 16% 34% 16% 5%	297
February	1st to 10th	Day	27% 31% 33% 7% 2 1	270
	11th to 20th	Day	27% 25% 35% 11% 1	267
	21st to end	Day	36% 26% 32% 7%	199
March	1st to 10th	Day	26% 20% 36% 14% 3 1	420
	11th to 20th	Day	23% 22% 35% 14% 5% 1	420
	21st to end	Day	30% 18% 29% 17% 5% 1	462
April	1st to 10th	Day	29% 19% 30% 15% 6% 1	420
	11th to 20th	Day	34% 17% 24% 16% 6% 4	412
	21st to end	Day	31% 14% 33% 15% 5% 2	420
May	1st to 10th	Day	30% 13% 27% 18% 8% 3	423
	11th to 20th	Day	24% 15% 31% 15% 11% 4	447
	21st to end	Day	20% 18% 31% 18% 11% 3	485
June	1st to 10th	Day	24% 13% 30% 26% 6% 1	486
	11th to 20th	Day	20% 15% 31% 23% 9% 2	630
	21st to end	Day	23% 13% 33% 21% 9% 1	630
July	1st to 10th	Day	14% 11% 33% 30% 11% 2	621
	11th to 20th	Day	17% 11% 29% 27% 13% 3	521
	21st to end	Day	14% 11% 31% 30% 11% 3	488
August	1st to 10th	Day	19% 7% 28% 28% 12% 6%	446
	11th to 20th	Day	17% 7% 26% 25% 16% 9%	439
	21st to end	Day	19% 11% 30% 21% 14% 5%	495
September	1st to 10th	Day	19% 11% 30% 22% 12% 6%	450
	11th to 20th	Day	20% 8% 26% 27% 15% 5%	450
	21st to end	Day	26% 12% 24% 22% 13% 3	450
October	1st to 10th	Day	28% 13% 24% 21% 11% 4	450
	11th to 20th	Day	32% 17% 32% 14% 3 2	450
	21st to end	Day	40% 15% 26% 16% 2 1	495
November	1st to 10th	Day	34% 18% 32% 15% 2	187
	11th to 20th	Day	31% 22% 33% 9% 4	180
	21st to end	Day	33% 17% 39% 8% 2 1	180
December	1st to 10th	Day	29% 17% 39% 13% 2	180
	11th to 20th	Day	39% 19% 28% 11% 2 1	180
	21st to end	Day	33% 23% 26% 16% 1 2	198
January	1st to 10th	Night	30% 16% 32% 18% 5%	948
	11th to 20th	Night	31% 16% 31% 17% 4	760
	21st to end	Night	22% 12% 35% 23% 8% 1	836
February	1st to 10th	Night	25% 18% 35% 18% 3	760
	11th to 20th	Night	22% 20% 33% 21% 4	742
	21st to end	Night	26% 21% 28% 23% 3	592
March	1st to 10th	Night	23% 19% 33% 20% 4	720
	11th to 20th	Night	23% 18% 35% 19% 5% 1	720
	21st to end	Night	23% 14% 29% 26% 8%	792
April	1st to 10th	Night	31% 12% 31% 21% 5%	720
	11th to 20th	Night	27% 12% 27% 23% 10% 1	627
	21st to end	Night	26% 11% 26% 25% 11% 1	540
May	1st to 10th	Night	24% 7% 26% 32% 11% 1	478
	11th to 20th	Night	21% 8% 31% 32% 8%	354
	21st to end	Night	12% 9% 37% 33% 9%	389
June	1st to 10th	Night	16% 9% 34% 32% 10%	360
	11th to 20th	Night	17% 9% 23% 39% 12%	360
	21st to end	Night	18% 8% 24% 36% 13% 1	360
July	1st to 10th	Night	13% 3 26% 41% 15% 1	350
	11th to 20th	Night	15% 5% 26% 35% 18%	348
	21st to end	Night	13% 5% 24% 40% 17% 1	456
August	1st to 10th	Night	17% 3 18% 38% 23% 2	537
	11th to 20th	Night	14% 4 17% 41% 22% 3	534
	21st to end	Night	19% 6% 24% 29% 18% 3	649
September	1st to 10th	Night	16% 7% 25% 32% 17% 3	720
	11th to 20th	Night	17% 8% 26% 28% 18% 4	720
	21st to end	Night	22% 8% 23% 27% 17% 3	720
October	1st to 10th	Night	26% 10% 26% 24% 12% 1	720
	11th to 20th	Night	31% 11% 29% 21% 7% 1	720
	21st to end	Night	38% 13% 28% 17% 3	792
November	1st to 10th	Night	35% 10% 25% 23% 6% 1	740
	11th to 20th	Night	29% 17% 27% 20% 6%	760
	21st to end	Night	36% 13% 28% 19% 4 1	760
December	1st to 10th	Night	33% 16% 30% 16% 4	760
	11th to 20th	Night	30% 18% 32% 14% 4 1	760
	21st to end	Night	35% 15% 29% 17% 3	978

Page generated at 2024-02-17 06:28:36. Version ac07

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