Musgrave Harbour
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Musgrave Harbour clear sky chart from 2005-11-06 to 2024-01-13.

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	22% 13% 5% 9% 7% 3 5% 4 5% 6% 22%	74609
	Night	23% 15% 6% 10% 7% 3 4 4 4 5% 18%	75139
Transparency	Day	63% 8% 12% 12% 5%	74297
	Night	67% 7% 10% 11% 4	74986
Seeing	Day	28% 11% 26% 24% 10% 1	16992
	Night	29% 12% 28% 22% 7% 1	23769

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% 17% 10% 16% 13% 4 5% 3 3 4 8%	1326
	11th to 20th	Day	17% 16% 7% 15% 16% 4 7% 4 4 4 8%	1380
	21st to end	Day	19% 13% 6% 15% 10% 5% 6% 5% 5% 4 12%	1584
February	1st to 10th	Day	19% 11% 5% 11% 15% 6% 6% 5% 4 6% 13%	1472
	11th to 20th	Day	18% 17% 6% 12% 11% 4 6% 5% 4 5% 13%	1577
	21st to end	Day	15% 12% 5% 12% 10% 6% 8% 5% 4 6% 18%	1480
March	1st to 10th	Day	17% 14% 5% 10% 7% 5% 5% 6% 5% 6% 21%	1796
	11th to 20th	Day	18% 15% 5% 9% 7% 5% 5% 4 5% 6% 20%	1960
	21st to end	Day	26% 15% 5% 9% 8% 3 3 4 4 5% 18%	2209
April	1st to 10th	Day	19% 13% 5% 9% 7% 4 4 6% 4 7% 23%	2187
	11th to 20th	Day	22% 14% 5% 8% 5% 2 4 4 4 7% 25%	2311
	21st to end	Day	20% 19% 6% 8% 5% 3 5% 4 4 5% 22%	2340
May	1st to 10th	Day	26% 15% 6% 8% 5% 3 4 4 4 5% 21%	2375
	11th to 20th	Day	24% 15% 5% 7% 6% 2 4 3 4 5% 24%	2624
	21st to end	Day	24% 13% 4 7% 6% 2 4 4 5% 6% 25%	2918
June	1st to 10th	Day	30% 13% 5% 8% 5% 3 4 4 4 6% 18%	2700
	11th to 20th	Day	28% 11% 4 6% 5% 3 4 4 5% 6% 24%	2700
	21st to end	Day	23% 9% 4 7% 6% 3 5% 4 5% 7% 25%	2700
July	1st to 10th	Day	20% 10% 3 6% 6% 3 5% 5% 5% 7% 30%	2700
	11th to 20th	Day	18% 8% 3 6% 6% 4 5% 5% 5% 7% 33%	2700
	21st to end	Day	19% 11% 4 8% 7% 4 5% 6% 5% 7% 25%	2796
August	1st to 10th	Day	23% 11% 3 6% 5% 3 4 5% 5% 7% 26%	2471
	11th to 20th	Day	20% 8% 3 7% 6% 3 4 4 6% 7% 30%	2305
	21st to end	Day	20% 8% 3 6% 5% 4 5% 5% 6% 7% 30%	2574
September	1st to 10th	Day	23% 7% 3 5% 5% 3 4 4 5% 7% 34%	2186
	11th to 20th	Day	27% 9% 4 6% 5% 3 3 3 5% 7% 28%	1980
	21st to end	Day	20% 9% 3 6% 5% 3 5% 4 5% 8% 31%	1980
October	1st to 10th	Day	24% 13% 3 7% 6% 3 4 4 4 6% 28%	1900
	11th to 20th	Day	24% 16% 4 9% 6% 3 5% 4 5% 7% 18%	1692
	21st to end	Day	29% 17% 4 8% 5% 3 4 4 4 5% 19%	1782
November	1st to 10th	Day	21% 20% 7% 8% 6% 4 5% 4 4 5% 16%	1609
	11th to 20th	Day	20% 18% 9% 7% 7% 2 4 3 5% 6% 18%	1520
	21st to end	Day	25% 14% 9% 11% 6% 2 5% 3 2 6% 16%	1335
December	1st to 10th	Day	21% 17% 9% 14% 8% 3 5% 3 4 4 12%	1330
	11th to 20th	Day	21% 18% 8% 14% 9% 3 4 4 4 4 11%	1668
	21st to end	Day	23% 18% 8% 24% 9% 4 3 3 2 3 4	2442
January	1st to 10th	Night	20% 15% 8% 17% 12% 5% 5% 4 4 4 7%	2839
	11th to 20th	Night	16% 16% 7% 17% 13% 5% 5% 4 4 5% 8%	2637
	21st to end	Night	18% 14% 6% 15% 11% 4 5% 4 4 4 14%	2772
February	1st to 10th	Night	17% 13% 5% 14% 14% 5% 6% 4 4 4 14%	2488
	11th to 20th	Night	19% 17% 6% 10% 10% 5% 5% 4 3 5% 15%	2266
	21st to end	Night	16% 12% 7% 11% 10% 4 6% 5% 5% 5% 20%	1776
March	1st to 10th	Night	18% 16% 5% 9% 7% 4 5% 5% 5% 6% 21%	2151
	11th to 20th	Night	16% 15% 5% 9% 8% 5% 5% 4 5% 6% 22%	1998
	21st to end	Night	26% 15% 5% 11% 7% 3 4 3 4 5% 18%	2142
April	1st to 10th	Night	24% 14% 6% 10% 7% 3 4 4 5% 6% 19%	1772
	11th to 20th	Night	24% 16% 6% 7% 4 3 3 4 4 5% 25%	1598
	21st to end	Night	26% 14% 5% 6% 6% 3 4 3 4 5% 24%	1620
May	1st to 10th	Night	27% 16% 4 8% 6% 3 4 4 3 5% 19%	1584
	11th to 20th	Night	27% 14% 6% 7% 5% 2 4 4 3 4 23%	1268
	21st to end	Night	27% 14% 4 7% 6% 3 3 4 4 6% 23%	1356
June	1st to 10th	Night	33% 10% 4 6% 6% 3 4 5% 4 5% 18%	1260
	11th to 20th	Night	30% 11% 4 6% 6% 3 5% 3 6% 7% 21%	1260
	21st to end	Night	27% 9% 3 6% 7% 2 4 5% 5% 7% 24%	1260
July	1st to 10th	Night	22% 11% 4 7% 5% 4 4 5% 5% 6% 28%	1260
	11th to 20th	Night	17% 9% 4 8% 7% 3 5% 5% 5% 7% 30%	1260
	21st to end	Night	20% 13% 3 8% 6% 3 4 5% 5% 7% 25%	1520
August	1st to 10th	Night	23% 10% 3 6% 6% 4 4 5% 6% 6% 26%	1466
	11th to 20th	Night	21% 10% 4 6% 5% 3 5% 5% 4 6% 31%	1595
	21st to end	Night	23% 8% 3 5% 5% 3 5% 5% 5% 8% 31%	1782
September	1st to 10th	Night	22% 9% 3 7% 4 4 3 4 5% 7% 33%	1772
	11th to 20th	Night	28% 9% 2 5% 5% 3 4 4 4 6% 29%	1980
	21st to end	Night	22% 12% 4 6% 5% 4 4 4 5% 6% 27%	1980
October	1st to 10th	Night	25% 12% 4 7% 5% 3 4 5% 5% 5% 25%	2060
	11th to 20th	Night	25% 16% 4 7% 5% 3 5% 4 5% 7% 20%	2264
	21st to end	Night	31% 18% 4 6% 5% 3 3 3 3 6% 19%	2574
November	1st to 10th	Night	23% 19% 5% 8% 7% 4 5% 4 4 5% 15%	2469
	11th to 20th	Night	23% 19% 8% 8% 5% 3 5% 4 3 7% 15%	2660
	21st to end	Night	21% 18% 8% 10% 6% 3 4 4 4 6% 15%	2844
December	1st to 10th	Night	21% 17% 10% 14% 7% 4 5% 3 3 4 12%	2850
	11th to 20th	Night	25% 21% 9% 19% 10% 3 4 2 2 2 5%	3531
	21st to end	Night	22% 16% 8% 21% 8% 3 3 3 3 3 9%	5225

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	78% 7% 9% 5% 1	1327
	11th to 20th	Day	75% 10% 9% 3 2	1380
	21st to end	Day	72% 7% 10% 7% 4	1584
February	1st to 10th	Day	70% 8% 10% 7% 3 1	1472
	11th to 20th	Day	73% 7% 9% 6% 4	1584
	21st to end	Day	65% 8% 10% 9% 7%	1480
March	1st to 10th	Day	62% 7% 12% 11% 8% 1	1800
	11th to 20th	Day	63% 7% 11% 12% 6% 1	1960
	21st to end	Day	68% 6% 9% 11% 5% 1	2209
April	1st to 10th	Day	60% 8% 12% 13% 6% 1	2187
	11th to 20th	Day	59% 6% 11% 15% 7% 1	2311
	21st to end	Day	64% 6% 10% 13% 7% 1	2340
May	1st to 10th	Day	67% 6% 9% 11% 6% 1	2375
	11th to 20th	Day	63% 7% 11% 11% 8% 1	2628
	21st to end	Day	59% 7% 13% 14% 6%	2918
June	1st to 10th	Day	70% 7% 9% 11% 4	2700
	11th to 20th	Day	62% 7% 11% 15% 4 1	2700
	21st to end	Day	59% 10% 13% 12% 5% 1	2700
July	1st to 10th	Day	53% 9% 15% 17% 6%	2625
	11th to 20th	Day	50% 9% 18% 18% 5%	2618
	21st to end	Day	56% 11% 15% 14% 4	2640
August	1st to 10th	Day	57% 9% 16% 16% 2	2457
	11th to 20th	Day	52% 11% 15% 16% 5%	2305
	21st to end	Day	52% 11% 18% 15% 3	2574
September	1st to 10th	Day	50% 7% 13% 22% 8% 1	2186
	11th to 20th	Day	56% 7% 14% 16% 6%	1980
	21st to end	Day	50% 9% 18% 18% 5%	1980
October	1st to 10th	Day	58% 8% 12% 15% 7%	1900
	11th to 20th	Day	66% 7% 14% 10% 3	1692
	21st to end	Day	69% 6% 8% 12% 4 1	1782
November	1st to 10th	Day	70% 8% 12% 8% 3	1609
	11th to 20th	Day	66% 7% 13% 10% 4 1	1520
	21st to end	Day	70% 6% 12% 9% 2	1335
December	1st to 10th	Day	74% 7% 9% 8% 2	1330
	11th to 20th	Day	77% 6% 11% 5% 1	1667
	21st to end	Day	85% 8% 4 3 1	2442
January	1st to 10th	Night	77% 9% 8% 4 2	2839
	11th to 20th	Night	77% 7% 9% 5% 2	2637
	21st to end	Night	71% 7% 9% 9% 4	2772
February	1st to 10th	Night	72% 7% 9% 8% 3	2488
	11th to 20th	Night	71% 6% 10% 9% 3	2270
	21st to end	Night	66% 7% 10% 11% 7% 1	1776
March	1st to 10th	Night	62% 7% 11% 13% 6% 1	2160
	11th to 20th	Night	61% 6% 13% 13% 6% 1	1999
	21st to end	Night	70% 4 7% 11% 8%	2142
April	1st to 10th	Night	66% 6% 9% 12% 7%	1772
	11th to 20th	Night	61% 5% 12% 15% 7% 1	1598
	21st to end	Night	64% 6% 8% 13% 8% 1	1620
May	1st to 10th	Night	70% 5% 8% 12% 6%	1584
	11th to 20th	Night	66% 6% 8% 14% 6%	1269
	21st to end	Night	64% 7% 11% 12% 6% 1	1357
June	1st to 10th	Night	69% 6% 10% 10% 4	1260
	11th to 20th	Night	62% 8% 13% 14% 4	1260
	21st to end	Night	59% 9% 13% 13% 5% 1	1260
July	1st to 10th	Night	57% 8% 14% 16% 4	1226
	11th to 20th	Night	53% 9% 15% 17% 6%	1218
	21st to end	Night	59% 8% 10% 19% 3	1436
August	1st to 10th	Night	55% 10% 14% 17% 3	1455
	11th to 20th	Night	53% 10% 15% 16% 6%	1595
	21st to end	Night	50% 9% 16% 19% 5%	1782
September	1st to 10th	Night	50% 8% 13% 19% 9%	1772
	11th to 20th	Night	57% 7% 12% 15% 8%	1980
	21st to end	Night	57% 7% 15% 16% 5%	1980
October	1st to 10th	Night	58% 8% 12% 15% 7% 1	2060
	11th to 20th	Night	62% 8% 12% 14% 4	2264
	21st to end	Night	70% 5% 9% 10% 5% 1	2574
November	1st to 10th	Night	70% 8% 9% 9% 4	2469
	11th to 20th	Night	70% 7% 11% 9% 3	2660
	21st to end	Night	69% 8% 12% 8% 3	2844
December	1st to 10th	Night	74% 7% 10% 8% 2	2850
	11th to 20th	Night	88% 5% 4 2 1	3533
	21st to end	Night	77% 9% 8% 5% 1	5225

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% 23% 30% 16% 6% 1	370
	11th to 20th	Day	24% 18% 36% 18% 4	349
	21st to end	Day	28% 18% 31% 18% 5%	374
February	1st to 10th	Day	26% 21% 34% 16% 3	340
	11th to 20th	Day	23% 20% 37% 18% 1 1	336
	21st to end	Day	21% 16% 38% 18% 6% 1	280
March	1st to 10th	Day	24% 16% 36% 20% 4 1	340
	11th to 20th	Day	24% 14% 28% 23% 10% 2	340
	21st to end	Day	32% 11% 29% 20% 5% 3	388
April	1st to 10th	Day	21% 17% 30% 23% 7% 1	447
	11th to 20th	Day	29% 9% 28% 24% 8% 2	589
	21st to end	Day	30% 10% 26% 28% 6% 1	600
May	1st to 10th	Day	32% 9% 27% 22% 9% 2	603
	11th to 20th	Day	27% 7% 25% 26% 12% 3	624
	21st to end	Day	31% 8% 21% 30% 8% 1	680
June	1st to 10th	Day	40% 8% 20% 23% 8% 1	630
	11th to 20th	Day	33% 7% 16% 30% 12% 2	630
	21st to end	Day	27% 4 22% 29% 15% 3	630
July	1st to 10th	Day	24% 7% 22% 32% 13% 2	620
	11th to 20th	Day	21% 4 21% 32% 21% 1	618
	21st to end	Day	25% 5% 20% 35% 14% 1	685
August	1st to 10th	Day	28% 4 19% 32% 15% 2	625
	11th to 20th	Day	24% 5% 20% 30% 18% 2	617
	21st to end	Day	25% 5% 20% 27% 18% 3	693
September	1st to 10th	Day	27% 7% 23% 29% 12% 2	496
	11th to 20th	Day	33% 11% 21% 27% 8% 1	360
	21st to end	Day	24% 13% 33% 21% 7% 2	360
October	1st to 10th	Day	24% 13% 37% 18% 8% 1	360
	11th to 20th	Day	33% 13% 21% 21% 11% 2	360
	21st to end	Day	32% 18% 23% 18% 8% 1	396
November	1st to 10th	Day	30% 20% 33% 15% 2	365
	11th to 20th	Day	29% 19% 28% 17% 5% 1	370
	21st to end	Day	33% 18% 33% 13% 3	370
December	1st to 10th	Day	26% 13% 36% 19% 5% 1	370
	11th to 20th	Day	31% 26% 27% 12% 3	370
	21st to end	Day	23% 17% 36% 16% 6% 1	407
January	1st to 10th	Night	26% 21% 32% 16% 5%	850
	11th to 20th	Night	24% 21% 34% 16% 4	814
	21st to end	Night	26% 17% 38% 15% 4	880
February	1st to 10th	Night	26% 19% 37% 16% 2	800
	11th to 20th	Night	28% 17% 37% 15% 3	779
	21st to end	Night	23% 12% 39% 18% 5% 2	592
March	1st to 10th	Night	25% 18% 33% 17% 6% 1	720
	11th to 20th	Night	22% 14% 31% 24% 9% 1	559
	21st to end	Night	32% 12% 28% 22% 6%	594
April	1st to 10th	Night	31% 12% 29% 21% 5% 2	540
	11th to 20th	Night	31% 8% 31% 22% 7% 1	534
	21st to end	Night	30% 7% 30% 28% 5%	540
May	1st to 10th	Night	35% 4 24% 26% 8% 2	540
	11th to 20th	Night	34% 4 27% 23% 11% 1	532
	21st to end	Night	34% 7% 25% 25% 8% 1	583
June	1st to 10th	Night	36% 7% 20% 29% 6% 1	540
	11th to 20th	Night	37% 4 17% 28% 13% 1	540
	21st to end	Night	31% 4 18% 34% 11% 2	540
July	1st to 10th	Night	26% 5% 23% 33% 12% 2	526
	11th to 20th	Night	23% 4 25% 35% 12% 1	522
	21st to end	Night	23% 7% 20% 38% 12% 1	590
August	1st to 10th	Night	29% 3 19% 33% 14% 1	538
	11th to 20th	Night	25% 7% 19% 29% 19% 1	532
	21st to end	Night	26% 4 18% 34% 16% 2	594
September	1st to 10th	Night	26% 4 26% 33% 10% 1	540
	11th to 20th	Night	31% 10% 26% 27% 6%	540
	21st to end	Night	30% 12% 31% 21% 6% 1	540
October	1st to 10th	Night	31% 9% 31% 23% 6% 1	580
	11th to 20th	Night	36% 11% 21% 24% 8%	734
	21st to end	Night	40% 11% 24% 19% 6% 1	891
November	1st to 10th	Night	33% 18% 29% 16% 3	830
	11th to 20th	Night	33% 15% 28% 17% 6% 1	850
	21st to end	Night	30% 21% 32% 14% 3	850
December	1st to 10th	Night	29% 15% 34% 17% 4 1	850
	11th to 20th	Night	32% 21% 30% 13% 3	850
	21st to end	Night	24% 21% 29% 19% 5% 1	935

Page generated at 2024-01-10 21:35:26. Version ac07

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