Melita
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Melita clear sky chart from 2005-11-06 to 2024-02-05.

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	11% 8% 4 7% 7% 4 5% 5% 6% 7% 37%	77828
	Night	9% 9% 4 8% 7% 4 5% 5% 6% 7% 36%	81080
Transparency	Day	46% 5% 16% 24% 9% 1	77519
	Night	47% 5% 15% 23% 10% 1	80911
Seeing	Day	14% 7% 29% 31% 16% 4	15078
	Night	14% 6% 31% 36% 13% 1	25217

By Month

Percentage Cloud Cover SW (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	6% 12% 6% 14% 10% 6% 6% 7% 8% 6% 18%	2284
	11th to 20th	Day	4 8% 6% 11% 14% 9% 12% 9% 7% 7% 14%	2540
	21st to end	Day	8% 11% 5% 12% 9% 4 5% 4 5% 6% 30%	2794
February	1st to 10th	Day	9% 12% 5% 11% 10% 5% 6% 4 6% 6% 26%	1472
	11th to 20th	Day	7% 13% 5% 8% 9% 5% 9% 6% 7% 9% 22%	1624
	21st to end	Day	8% 9% 5% 11% 9% 4 7% 6% 6% 8% 25%	1480
March	1st to 10th	Day	9% 14% 7% 13% 12% 5% 6% 5% 5% 6% 19%	1800
	11th to 20th	Day	7% 10% 6% 8% 7% 5% 6% 5% 6% 7% 32%	1894
	21st to end	Day	12% 10% 5% 8% 8% 4 6% 5% 6% 8% 27%	2290
April	1st to 10th	Day	9% 9% 4 6% 6% 3 5% 4 6% 8% 39%	2160
	11th to 20th	Day	15% 11% 4 8% 5% 3 4 5% 6% 7% 32%	2265
	21st to end	Day	14% 9% 4 8% 6% 3 5% 5% 5% 7% 35%	2340
May	1st to 10th	Day	14% 7% 2 6% 6% 3 4 4 6% 6% 42%	2452
	11th to 20th	Day	16% 7% 3 5% 5% 3 5% 5% 5% 8% 38%	2508
	21st to end	Day	18% 7% 3 5% 6% 3 5% 5% 7% 8% 33%	2918
June	1st to 10th	Day	13% 5% 3 5% 4 3 5% 5% 6% 8% 43%	2700
	11th to 20th	Day	16% 6% 3 6% 5% 3 5% 6% 7% 8% 36%	2700
	21st to end	Day	11% 5% 2 5% 6% 4 5% 5% 6% 10% 40%	2700
July	1st to 10th	Day	7% 5% 2 4 4 3 5% 5% 5% 10% 51%	2700
	11th to 20th	Day	7% 4 2 5% 5% 3 5% 6% 6% 8% 48%	2613
	21st to end	Day	5% 3 1 4 4 3 5% 5% 7% 9% 55%	2742
August	1st to 10th	Day	9% 5% 2 4 4 3 5% 5% 6% 8% 49%	2507
	11th to 20th	Day	9% 4 2 4 5% 3 4 4 6% 9% 48%	2358
	21st to end	Day	10% 4 2 4 4 2 4 4 5% 8% 53%	2534
September	1st to 10th	Day	10% 5% 2 5% 4 3 3 4 5% 7% 51%	2160
	11th to 20th	Day	14% 5% 2 5% 5% 3 3 4 5% 6% 49%	2021
	21st to end	Day	16% 5% 2 4 4 2 4 5% 4 7% 47%	1980
October	1st to 10th	Day	17% 11% 4 7% 5% 3 3 3 5% 6% 37%	1949
	11th to 20th	Day	12% 11% 3 6% 5% 2 3 4 6% 7% 41%	1620
	21st to end	Day	15% 11% 5% 9% 4 3 4 5% 6% 6% 33%	1782
November	1st to 10th	Day	15% 12% 4 8% 6% 2 4 5% 5% 6% 31%	1673
	11th to 20th	Day	10% 14% 6% 10% 9% 3 4 4 5% 6% 28%	1483
	21st to end	Day	8% 13% 5% 9% 8% 4 6% 6% 6% 5% 30%	1330
December	1st to 10th	Day	6% 14% 6% 11% 11% 6% 6% 5% 5% 6% 23%	1330
	11th to 20th	Day	11% 15% 6% 11% 9% 4 6% 5% 6% 7% 21%	1683
	21st to end	Day	6% 7% 4 10% 7% 5% 6% 8% 6% 7% 35%	2442
January	1st to 10th	Night	7% 13% 6% 15% 8% 5% 6% 6% 6% 5% 23%	4669
	11th to 20th	Night	5% 8% 4 12% 14% 8% 9% 7% 6% 8% 20%	4430
	21st to end	Night	8% 11% 6% 12% 9% 4 6% 6% 5% 6% 27%	4873
February	1st to 10th	Night	8% 11% 5% 10% 8% 4 7% 6% 7% 6% 28%	2583
	11th to 20th	Night	7% 10% 5% 8% 10% 4 6% 7% 6% 7% 31%	2238
	21st to end	Night	7% 10% 5% 9% 6% 4 5% 5% 6% 7% 36%	1776
March	1st to 10th	Night	10% 11% 7% 10% 8% 4 5% 6% 6% 6% 27%	2160
	11th to 20th	Night	6% 10% 5% 7% 7% 3 6% 5% 6% 7% 38%	2066
	21st to end	Night	9% 11% 5% 8% 6% 3 5% 5% 6% 7% 35%	2066
April	1st to 10th	Night	5% 8% 3 7% 6% 3 6% 5% 6% 8% 43%	1800
	11th to 20th	Night	15% 10% 4 6% 6% 3 5% 4 5% 7% 35%	1642
	21st to end	Night	14% 7% 3 7% 6% 3 6% 4 5% 8% 38%	1620
May	1st to 10th	Night	12% 7% 3 5% 5% 3 4 5% 6% 8% 43%	1504
	11th to 20th	Night	12% 5% 2 6% 6% 3 5% 6% 6% 8% 41%	1385
	21st to end	Night	17% 6% 2 6% 5% 4 4 4 6% 8% 37%	1358
June	1st to 10th	Night	15% 3 1 5% 4 3 4 6% 7% 9% 43%	1260
	11th to 20th	Night	12% 5% 3 5% 6% 3 6% 5% 6% 7% 42%	1260
	21st to end	Night	10% 4 1 5% 4 3 5% 6% 6% 9% 46%	1260
July	1st to 10th	Night	6% 3 1 3 3 2 4 4 6% 11% 56%	1260
	11th to 20th	Night	6% 2 2 3 4 2 4 4 7% 10% 57%	1344
	21st to end	Night	4 2 1 3 4 2 4 4 5% 8% 61%	1576
August	1st to 10th	Night	6% 3 2 3 4 2 4 4 7% 8% 57%	1432
	11th to 20th	Night	6% 3 2 4 4 2 4 4 7% 9% 55%	1542
	21st to end	Night	9% 4 2 3 4 2 4 3 4 6% 59%	1820
September	1st to 10th	Night	8% 4 2 4 5% 2 4 4 5% 7% 55%	1800
	11th to 20th	Night	12% 4 2 4 3 2 4 4 6% 8% 50%	1939
	21st to end	Night	15% 7% 3 4 5% 3 3 4 4 7% 44%	1980
October	1st to 10th	Night	14% 8% 3 6% 5% 3 4 5% 4 6% 43%	1998
	11th to 20th	Night	15% 9% 3 7% 4 3 4 4 5% 6% 41%	2330
	21st to end	Night	13% 10% 4 7% 5% 4 5% 4 6% 6% 36%	2574
November	1st to 10th	Night	13% 10% 5% 7% 6% 3 5% 5% 5% 7% 35%	2405
	11th to 20th	Night	9% 10% 6% 12% 8% 4 5% 4 4 7% 32%	2691
	21st to end	Night	9% 11% 4 9% 8% 4 5% 4 6% 6% 34%	2850
December	1st to 10th	Night	7% 11% 6% 11% 9% 5% 7% 6% 5% 6% 27%	2850
	11th to 20th	Night	9% 15% 6% 12% 9% 4 6% 5% 4 7% 23%	3514
	21st to end	Night	7% 10% 4 8% 7% 4 7% 7% 6% 7% 34%	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	62% 5% 16% 12% 4	2285
	11th to 20th	Day	66% 4 14% 12% 3	2540
	21st to end	Day	56% 3 12% 23% 6%	2794
February	1st to 10th	Day	59% 3 14% 17% 6%	1472
	11th to 20th	Day	56% 5% 14% 16% 8%	1633
	21st to end	Day	56% 4 14% 19% 6% 1	1480
March	1st to 10th	Day	65% 6% 13% 11% 5%	1800
	11th to 20th	Day	51% 6% 15% 21% 7%	1894
	21st to end	Day	55% 7% 16% 17% 5%	2290
April	1st to 10th	Day	41% 3 17% 26% 12% 1	2160
	11th to 20th	Day	51% 4 12% 20% 12% 1	2268
	21st to end	Day	48% 5% 17% 22% 7%	2340
May	1st to 10th	Day	42% 4 14% 27% 12% 1	2452
	11th to 20th	Day	43% 5% 12% 27% 12% 1	2512
	21st to end	Day	47% 5% 15% 23% 9%	2918
June	1st to 10th	Day	39% 4 21% 26% 8% 1	2700
	11th to 20th	Day	44% 6% 18% 23% 8% 1	2700
	21st to end	Day	39% 6% 21% 26% 7% 1	2700
July	1st to 10th	Day	29% 5% 21% 34% 10% 1	2626
	11th to 20th	Day	32% 6% 17% 32% 12% 1	2532
	21st to end	Day	25% 5% 19% 36% 14% 1	2590
August	1st to 10th	Day	32% 5% 19% 32% 10% 1	2491
	11th to 20th	Day	31% 5% 22% 32% 10% 1	2358
	21st to end	Day	30% 4 14% 38% 13% 1	2534
September	1st to 10th	Day	33% 4 17% 32% 14% 1	2160
	11th to 20th	Day	38% 4 19% 25% 13% 1	2021
	21st to end	Day	38% 4 14% 31% 13%	1980
October	1st to 10th	Day	49% 3 13% 24% 9% 1	1949
	11th to 20th	Day	42% 3 16% 29% 10%	1620
	21st to end	Day	52% 4 16% 21% 7% 1	1782
November	1st to 10th	Day	53% 4 16% 18% 7% 1	1673
	11th to 20th	Day	57% 4 16% 15% 7% 1	1483
	21st to end	Day	55% 6% 16% 17% 5%	1330
December	1st to 10th	Day	62% 4 14% 15% 5%	1330
	11th to 20th	Day	62% 4 16% 15% 3	1680
	21st to end	Day	45% 5% 13% 25% 11% 1	2442
January	1st to 10th	Night	61% 4 13% 18% 4	4669
	11th to 20th	Night	63% 3 16% 14% 4	4430
	21st to end	Night	57% 6% 14% 19% 4	4873
February	1st to 10th	Night	54% 4 16% 19% 7%	2583
	11th to 20th	Night	50% 5% 15% 18% 11%	2239
	21st to end	Night	47% 3 14% 24% 11%	1776
March	1st to 10th	Night	57% 5% 15% 17% 6%	2160
	11th to 20th	Night	43% 5% 15% 27% 9% 1	2066
	21st to end	Night	48% 6% 17% 22% 7%	2066
April	1st to 10th	Night	38% 5% 12% 27% 16% 3	1800
	11th to 20th	Night	50% 4 9% 22% 14% 1	1642
	21st to end	Night	46% 4 12% 24% 12% 2	1620
May	1st to 10th	Night	38% 4 14% 25% 17% 1	1504
	11th to 20th	Night	40% 5% 12% 26% 16% 1	1386
	21st to end	Night	44% 5% 15% 24% 11% 1	1358
June	1st to 10th	Night	37% 6% 16% 26% 13% 2	1260
	11th to 20th	Night	40% 5% 17% 25% 12% 2	1260
	21st to end	Night	33% 7% 20% 32% 8% 1	1260
July	1st to 10th	Night	24% 4 21% 33% 16% 2	1225
	11th to 20th	Night	23% 5% 19% 36% 15% 1	1302
	21st to end	Night	21% 5% 18% 35% 19% 3	1488
August	1st to 10th	Night	24% 4 21% 36% 12% 3	1424
	11th to 20th	Night	26% 5% 21% 35% 11% 2	1542
	21st to end	Night	27% 3 13% 35% 20% 2	1820
September	1st to 10th	Night	29% 4 12% 33% 19% 2	1800
	11th to 20th	Night	33% 4 17% 29% 15% 2	1939
	21st to end	Night	40% 4 12% 30% 12% 1	1980
October	1st to 10th	Night	43% 4 16% 25% 10% 1	1998
	11th to 20th	Night	45% 3 12% 28% 12% 1	2330
	21st to end	Night	48% 4 15% 24% 9%	2574
November	1st to 10th	Night	48% 5% 14% 21% 8% 2	2405
	11th to 20th	Night	53% 5% 16% 20% 6%	2691
	21st to end	Night	51% 5% 20% 18% 6%	2850
December	1st to 10th	Night	56% 5% 17% 16% 6%	2850
	11th to 20th	Night	62% 3 17% 13% 5% 1	3516
	21st to end	Night	47% 6% 12% 22% 12% 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	11% 5% 32% 33% 15% 4	270
	11th to 20th	Day	10% 7% 36% 33% 11% 2	270
	21st to end	Day	14% 7% 31% 34% 12% 2	297
February	1st to 10th	Day	11% 8% 36% 36% 10%	252
	11th to 20th	Day	10% 6% 38% 32% 12% 2	240
	21st to end	Day	5% 5% 28% 43% 16% 4	198
March	1st to 10th	Day	10% 10% 38% 30% 9% 4	240
	11th to 20th	Day	12% 6% 32% 29% 17% 4	240
	21st to end	Day	16% 7% 29% 27% 19% 3	376
April	1st to 10th	Day	12% 10% 35% 30% 9% 2	420
	11th to 20th	Day	20% 7% 31% 28% 13% 1	546
	21st to end	Day	17% 8% 26% 32% 16% 2	600
May	1st to 10th	Day	13% 8% 30% 33% 14% 3	603
	11th to 20th	Day	18% 8% 26% 28% 16% 4	625
	21st to end	Day	18% 9% 22% 31% 17% 3	679
June	1st to 10th	Day	13% 8% 27% 30% 17% 5%	630
	11th to 20th	Day	15% 10% 30% 28% 13% 4	630
	21st to end	Day	11% 9% 22% 35% 20% 4	630
July	1st to 10th	Day	9% 5% 23% 36% 22% 6%	621
	11th to 20th	Day	9% 6% 32% 31% 17% 5%	618
	21st to end	Day	5% 3 27% 36% 23% 7%	684
August	1st to 10th	Day	10% 4 21% 37% 21% 7%	626
	11th to 20th	Day	10% 6% 20% 29% 27% 7%	615
	21st to end	Day	11% 6% 23% 34% 21% 5%	653
September	1st to 10th	Day	11% 9% 36% 27% 14% 3	450
	11th to 20th	Day	18% 9% 26% 30% 15% 1	311
	21st to end	Day	24% 10% 27% 26% 12% 1	270
October	1st to 10th	Day	23% 8% 29% 25% 12% 4	270
	11th to 20th	Day	19% 12% 28% 27% 10% 4	270
	21st to end	Day	26% 5% 39% 21% 6% 3	297
November	1st to 10th	Day	26% 8% 24% 29% 11% 2	270
	11th to 20th	Day	16% 11% 39% 25% 9% 1	270
	21st to end	Day	14% 9% 36% 31% 8% 2	270
December	1st to 10th	Day	11% 8% 35% 30% 14% 2	270
	11th to 20th	Day	17% 9% 40% 27% 5% 2	270
	21st to end	Day	10% 4 36% 32% 13% 5%	297
January	1st to 10th	Night	12% 5% 35% 33% 13% 1	950
	11th to 20th	Night	15% 7% 34% 35% 8% 1	950
	21st to end	Night	12% 8% 34% 36% 9%	1045
February	1st to 10th	Night	13% 7% 30% 35% 12% 2	923
	11th to 20th	Night	13% 6% 31% 36% 12% 2	798
	21st to end	Night	11% 5% 27% 39% 15% 2	592
March	1st to 10th	Night	14% 7% 32% 31% 13% 3	720
	11th to 20th	Night	10% 7% 32% 36% 14% 2	626
	21st to end	Night	13% 6% 30% 35% 13% 3	594
April	1st to 10th	Night	9% 7% 38% 35% 10% 1	540
	11th to 20th	Night	20% 6% 27% 39% 8% 1	533
	21st to end	Night	16% 5% 30% 34% 14% 1	540
May	1st to 10th	Night	15% 5% 28% 37% 15%	540
	11th to 20th	Night	16% 3 31% 37% 13%	531
	21st to end	Night	20% 5% 25% 37% 13% 1	584
June	1st to 10th	Night	15% 4 31% 32% 18% 1	540
	11th to 20th	Night	15% 4 31% 35% 14% 1	540
	21st to end	Night	11% 4 25% 41% 18% 1	540
July	1st to 10th	Night	7% 2 20% 47% 23%	525
	11th to 20th	Night	7% 4 27% 47% 14% 1	522
	21st to end	Night	6% 2 23% 51% 16% 2	591
August	1st to 10th	Night	8% 4 21% 47% 18% 1	537
	11th to 20th	Night	7% 3 21% 43% 23% 3	534
	21st to end	Night	11% 3 28% 41% 17% 1	594
September	1st to 10th	Night	9% 5% 28% 37% 18% 3	540
	11th to 20th	Night	14% 4 33% 37% 11% 1	540
	21st to end	Night	18% 5% 31% 31% 14% 1	540
October	1st to 10th	Night	18% 6% 33% 32% 11%	558
	11th to 20th	Night	19% 7% 28% 33% 11% 1	890
	21st to end	Night	18% 8% 32% 32% 10% 1	990
November	1st to 10th	Night	18% 8% 33% 32% 8% 1	925
	11th to 20th	Night	14% 9% 35% 30% 9% 2	950
	21st to end	Night	13% 9% 38% 32% 7%	950
December	1st to 10th	Night	12% 7% 35% 32% 13% 3	950
	11th to 20th	Night	16% 8% 32% 31% 11% 1	950
	21st to end	Night	18% 5% 31% 33% 12% 2	1045

Page generated at 2024-02-02 04:20:33. Version ac07

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