Augusta
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Augusta clear sky chart from 2005-11-06 to 2024-04-03.

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% 7% 3 5% 5% 3 4 4 5% 7% 38%	78432
	Night	18% 8% 3 5% 5% 3 4 4 5% 6% 38%	81678
Transparency	Day	45% 7% 12% 21% 13% 2	78137
	Night	46% 7% 12% 21% 13% 2	81508
Seeing	Day	24% 17% 31% 19% 8% 2	14462
	Night	23% 13% 32% 24% 7%	23297

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% 8% 3 5% 5% 3 4 5% 4 6% 41%	2517
	11th to 20th	Day	18% 7% 3 6% 4 3 4 4 5% 5% 42%	2520
	21st to end	Day	16% 12% 3 7% 5% 3 4 4 5% 6% 36%	2772
February	1st to 10th	Day	17% 10% 4 6% 4 3 5% 3 5% 6% 36%	1685
	11th to 20th	Day	12% 9% 4 8% 6% 3 5% 4 5% 6% 37%	1824
	21st to end	Day	16% 10% 3 6% 5% 3 5% 5% 5% 5% 36%	1570
March	1st to 10th	Day	17% 10% 3 6% 5% 4 5% 4 5% 6% 36%	1897
	11th to 20th	Day	17% 6% 3 6% 6% 4 4 3 3 6% 41%	2061
	21st to end	Day	19% 8% 3 5% 5% 2 3 4 5% 5% 40%	2337
April	1st to 10th	Day	20% 10% 4 6% 5% 3 4 4 3 6% 35%	2184
	11th to 20th	Day	18% 6% 3 4 5% 3 5% 4 6% 7% 39%	2244
	21st to end	Day	23% 8% 3 7% 5% 3 4 4 5% 6% 32%	2340
May	1st to 10th	Day	25% 8% 2 5% 5% 2 4 5% 4 6% 33%	2340
	11th to 20th	Day	20% 7% 3 5% 5% 4 4 4 4 7% 37%	2326
	21st to end	Day	18% 6% 3 6% 5% 3 5% 4 6% 7% 37%	2725
June	1st to 10th	Day	23% 7% 3 5% 5% 3 4 5% 6% 8% 31%	2605
	11th to 20th	Day	19% 6% 3 5% 5% 3 4 5% 5% 8% 38%	2700
	21st to end	Day	24% 6% 3 5% 5% 4 6% 5% 6% 8% 30%	2591
July	1st to 10th	Day	16% 6% 2 5% 4 3 5% 5% 7% 8% 39%	2520
	11th to 20th	Day	13% 6% 3 5% 6% 3 5% 7% 7% 8% 37%	2520
	21st to end	Day	14% 6% 2 6% 5% 4 5% 6% 7% 8% 37%	2744
August	1st to 10th	Day	13% 5% 2 5% 6% 4 6% 5% 6% 9% 40%	2337
	11th to 20th	Day	14% 7% 2 6% 5% 4 6% 4 6% 9% 38%	2304
	21st to end	Day	13% 4 2 5% 4 3 4 5% 6% 8% 46%	2499
September	1st to 10th	Day	13% 4 2 4 4 3 5% 4 6% 7% 47%	2106
	11th to 20th	Day	13% 5% 2 4 3 2 3 4 5% 5% 54%	1980
	21st to end	Day	17% 4 2 4 5% 2 3 4 5% 9% 45%	1980
October	1st to 10th	Day	19% 7% 2 5% 6% 3 4 4 4 6% 40%	1973
	11th to 20th	Day	20% 6% 2 5% 5% 3 4 5% 4 6% 40%	1738
	21st to end	Day	23% 8% 3 5% 4 3 4 4 4 6% 36%	1782
November	1st to 10th	Day	18% 6% 2 5% 4 2 4 4 4 6% 44%	1671
	11th to 20th	Day	20% 6% 2 4 4 2 4 4 4 7% 42%	1710
	21st to end	Day	22% 7% 2 5% 3 2 3 3 4 6% 43%	1615
December	1st to 10th	Day	23% 11% 2 5% 4 3 4 3 4 6% 35%	1364
	11th to 20th	Day	23% 9% 2 4 5% 2 4 4 4 5% 38%	1668
	21st to end	Day	25% 12% 3 4 5% 3 4 4 5% 5% 30%	2683
January	1st to 10th	Night	15% 9% 4 6% 5% 3 4 4 4 6% 40%	4429
	11th to 20th	Night	14% 10% 3 8% 6% 3 4 5% 5% 7% 35%	4440
	21st to end	Night	18% 11% 4 7% 6% 3 4 5% 4 6% 34%	4884
February	1st to 10th	Night	16% 8% 4 7% 6% 4 5% 5% 5% 6% 34%	2494
	11th to 20th	Night	12% 10% 4 6% 6% 3 5% 5% 5% 6% 39%	2240
	21st to end	Night	15% 9% 4 6% 5% 3 5% 4 4 6% 39%	1884
March	1st to 10th	Night	17% 11% 3 5% 6% 3 5% 4 4 6% 36%	2270
	11th to 20th	Night	17% 7% 4 6% 7% 3 4 5% 5% 6% 36%	2118
	21st to end	Night	18% 9% 3 6% 4 2 4 4 5% 5% 39%	2259
April	1st to 10th	Night	21% 11% 4 4 5% 3 4 4 4 5% 35%	1821
	11th to 20th	Night	19% 6% 3 5% 5% 3 4 5% 5% 6% 38%	1665
	21st to end	Night	25% 8% 3 5% 5% 2 4 4 5% 5% 34%	1620
May	1st to 10th	Night	20% 9% 4 5% 6% 3 5% 4 6% 8% 30%	1620
	11th to 20th	Night	21% 6% 3 5% 5% 3 5% 5% 6% 8% 32%	1582
	21st to end	Night	20% 8% 3 5% 6% 3 5% 5% 4 7% 35%	1550
June	1st to 10th	Night	24% 7% 3 6% 6% 3 4 4 5% 6% 32%	1346
	11th to 20th	Night	17% 6% 3 6% 3 3 4 5% 5% 9% 38%	1260
	21st to end	Night	24% 7% 2 5% 4 2 4 5% 7% 8% 32%	1360
July	1st to 10th	Night	16% 7% 3 4 5% 4 5% 5% 5% 9% 37%	1440
	11th to 20th	Night	15% 8% 2 5% 5% 2 4 5% 7% 9% 38%	1440
	21st to end	Night	16% 4 3 3 5% 2 6% 5% 7% 9% 39%	1574
August	1st to 10th	Night	13% 5% 3 5% 4 3 5% 6% 6% 8% 43%	1584
	11th to 20th	Night	14% 6% 3 5% 5% 3 5% 5% 6% 10% 37%	1596
	21st to end	Night	13% 5% 2 4 5% 2 4 4 6% 6% 48%	1854
September	1st to 10th	Night	14% 5% 2 4 4 2 5% 4 4 7% 49%	1853
	11th to 20th	Night	16% 6% 2 4 3 2 3 3 4 6% 51%	1980
	21st to end	Night	16% 6% 2 4 4 3 5% 3 4 7% 46%	1980
October	1st to 10th	Night	18% 6% 3 5% 5% 3 4 5% 5% 6% 40%	1986
	11th to 20th	Night	18% 5% 3 5% 5% 4 5% 4 4 6% 40%	2219
	21st to end	Night	26% 7% 2 4 4 3 4 3 4 6% 37%	2574
November	1st to 10th	Night	18% 6% 2 5% 4 3 4 3 5% 6% 43%	2407
	11th to 20th	Night	18% 5% 2 5% 4 3 5% 4 4 6% 42%	2470
	21st to end	Night	17% 7% 3 5% 5% 3 4 4 5% 6% 41%	2561
December	1st to 10th	Night	22% 9% 3 6% 6% 3 5% 4 5% 5% 33%	2816
	11th to 20th	Night	23% 7% 3 4 5% 3 4 3 4 5% 38%	3531
	21st to end	Night	26% 9% 3 5% 4 3 3 4 4 6% 33%	4971

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	42% 8% 13% 26% 10% 1	2518
	11th to 20th	Day	42% 7% 13% 24% 11% 2	2520
	21st to end	Day	48% 6% 13% 19% 13% 1	2772
February	1st to 10th	Day	48% 6% 11% 20% 13% 2	1685
	11th to 20th	Day	48% 6% 11% 20% 12% 3	1833
	21st to end	Day	48% 6% 11% 19% 11% 5%	1570
March	1st to 10th	Day	48% 5% 13% 16% 14% 4	1900
	11th to 20th	Day	43% 6% 10% 21% 16% 4	2061
	21st to end	Day	45% 6% 9% 18% 17% 5%	2337
April	1st to 10th	Day	51% 5% 9% 16% 15% 4	2184
	11th to 20th	Day	43% 7% 11% 22% 14% 3	2244
	21st to end	Day	53% 6% 9% 17% 12% 4	2340
May	1st to 10th	Day	51% 6% 8% 20% 13% 2	2340
	11th to 20th	Day	47% 6% 9% 19% 16% 3	2330
	21st to end	Day	44% 8% 14% 21% 11% 2	2725
June	1st to 10th	Day	50% 8% 13% 20% 9%	2605
	11th to 20th	Day	44% 8% 12% 19% 15% 3	2700
	21st to end	Day	51% 9% 12% 17% 10% 1	2591
July	1st to 10th	Day	41% 8% 14% 23% 13% 1	2450
	11th to 20th	Day	41% 10% 15% 23% 10% 1	2445
	21st to end	Day	40% 10% 16% 22% 11% 1	2591
August	1st to 10th	Day	40% 9% 16% 24% 10%	2323
	11th to 20th	Day	43% 7% 15% 24% 11%	2304
	21st to end	Day	35% 8% 14% 23% 18% 1	2499
September	1st to 10th	Day	35% 7% 14% 25% 17% 1	2106
	11th to 20th	Day	32% 5% 10% 29% 22% 2	1980
	21st to end	Day	37% 7% 12% 27% 16% 1	1980
October	1st to 10th	Day	45% 6% 10% 23% 14% 2	1973
	11th to 20th	Day	44% 6% 13% 26% 10% 1	1738
	21st to end	Day	50% 5% 11% 20% 13% 2	1782
November	1st to 10th	Day	41% 6% 14% 23% 15% 2	1671
	11th to 20th	Day	41% 6% 11% 21% 18% 3	1710
	21st to end	Day	43% 5% 16% 23% 11% 1	1615
December	1st to 10th	Day	51% 5% 10% 20% 12% 1	1364
	11th to 20th	Day	47% 6% 9% 20% 13% 4	1668
	21st to end	Day	56% 6% 10% 17% 8% 3	2683
January	1st to 10th	Night	44% 6% 12% 27% 10% 2	4429
	11th to 20th	Night	47% 7% 15% 18% 11% 2	4440
	21st to end	Night	51% 6% 10% 19% 12% 1	4884
February	1st to 10th	Night	49% 6% 13% 17% 12% 3	2494
	11th to 20th	Night	45% 5% 10% 21% 15% 3	2242
	21st to end	Night	46% 6% 10% 21% 14% 4	1884
March	1st to 10th	Night	49% 5% 8% 20% 14% 3	2280
	11th to 20th	Night	48% 6% 12% 17% 13% 4	2119
	21st to end	Night	46% 6% 8% 18% 19% 4	2259
April	1st to 10th	Night	51% 5% 9% 17% 15% 4	1821
	11th to 20th	Night	44% 6% 11% 22% 16% 1	1665
	21st to end	Night	52% 6% 12% 16% 11% 4	1620
May	1st to 10th	Night	52% 6% 9% 18% 13% 2	1620
	11th to 20th	Night	48% 9% 10% 18% 12% 3	1583
	21st to end	Night	50% 7% 12% 18% 12% 1	1551
June	1st to 10th	Night	53% 6% 11% 20% 9% 1	1346
	11th to 20th	Night	43% 8% 14% 20% 13% 2	1260
	21st to end	Night	48% 10% 15% 17% 9% 2	1360
July	1st to 10th	Night	42% 9% 15% 22% 12% 1	1400
	11th to 20th	Night	41% 8% 17% 24% 10%	1392
	21st to end	Night	39% 10% 17% 24% 9% 1	1486
August	1st to 10th	Night	38% 9% 18% 25% 10%	1574
	11th to 20th	Night	40% 10% 17% 20% 12%	1596
	21st to end	Night	35% 7% 13% 27% 16% 1	1854
September	1st to 10th	Night	35% 6% 15% 28% 15%	1853
	11th to 20th	Night	34% 5% 12% 28% 18% 2	1980
	21st to end	Night	37% 6% 11% 29% 14% 2	1980
October	1st to 10th	Night	43% 8% 12% 22% 14% 1	1986
	11th to 20th	Night	43% 7% 13% 25% 11% 1	2219
	21st to end	Night	49% 5% 12% 19% 13% 1	2574
November	1st to 10th	Night	42% 6% 11% 25% 14% 1	2407
	11th to 20th	Night	43% 5% 11% 23% 16% 2	2470
	21st to end	Night	43% 7% 14% 21% 14% 2	2561
December	1st to 10th	Night	53% 5% 10% 20% 11% 1	2816
	11th to 20th	Night	47% 6% 10% 19% 17% 1	3532
	21st to end	Night	51% 7% 11% 19% 11% 1	4971

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	31% 18% 29% 19% 4	180
	11th to 20th	Day	31% 23% 27% 14% 3 2	180
	21st to end	Day	21% 23% 37% 17% 2	198
February	1st to 10th	Day	30% 19% 29% 21% 2	345
	11th to 20th	Day	26% 26% 33% 13% 1	444
	21st to end	Day	26% 21% 33% 16% 4	382
March	1st to 10th	Day	27% 22% 34% 14% 3	460
	11th to 20th	Day	25% 27% 30% 14% 3 1	460
	21st to end	Day	28% 26% 26% 12% 6% 2	506
April	1st to 10th	Day	33% 19% 30% 11% 5% 1	428
	11th to 20th	Day	27% 25% 27% 14% 5% 2	412
	21st to end	Day	31% 21% 29% 13% 4 1	420
May	1st to 10th	Day	33% 18% 30% 15% 3 1	423
	11th to 20th	Day	21% 20% 36% 15% 6% 2	447
	21st to end	Day	21% 18% 38% 17% 6%	485
June	1st to 10th	Day	22% 14% 34% 19% 9% 1	535
	11th to 20th	Day	21% 15% 30% 21% 12% 1	630
	21st to end	Day	24% 12% 30% 23% 9% 2	521
July	1st to 10th	Day	18% 11% 38% 23% 8% 2	445
	11th to 20th	Day	14% 9% 39% 24% 10% 4	444
	21st to end	Day	15% 9% 39% 26% 9% 3	488
August	1st to 10th	Day	13% 8% 33% 32% 13% 2	446
	11th to 20th	Day	17% 8% 30% 26% 14% 4	439
	21st to end	Day	14% 13% 31% 26% 13% 3	495
September	1st to 10th	Day	16% 9% 31% 27% 14% 4	450
	11th to 20th	Day	19% 13% 31% 18% 13% 6%	450
	21st to end	Day	18% 15% 30% 22% 11% 5%	450
October	1st to 10th	Day	22% 16% 26% 22% 12% 3	446
	11th to 20th	Day	25% 13% 33% 17% 11% 2	360
	21st to end	Day	34% 12% 28% 19% 6% 1	396
November	1st to 10th	Day	25% 15% 30% 21% 8% 2	365
	11th to 20th	Day	32% 14% 29% 20% 4 1	370
	21st to end	Day	30% 18% 26% 17% 7% 1	370
December	1st to 10th	Day	27% 19% 35% 15% 4	214
	11th to 20th	Day	36% 24% 29% 8% 2	180
	21st to end	Day	36% 20% 26% 12% 6%	198
January	1st to 10th	Night	23% 15% 37% 22% 3	760
	11th to 20th	Night	28% 17% 34% 18% 4	760
	21st to end	Night	20% 18% 39% 20% 3	836
February	1st to 10th	Night	22% 19% 34% 22% 3	760
	11th to 20th	Night	20% 21% 39% 18% 2	743
	21st to end	Night	23% 16% 37% 21% 3	628
March	1st to 10th	Night	27% 16% 38% 18% 2	760
	11th to 20th	Night	22% 19% 34% 19% 6%	760
	21st to end	Night	25% 18% 33% 20% 4	836
April	1st to 10th	Night	29% 18% 32% 18% 4	729
	11th to 20th	Night	23% 16% 34% 22% 4	601
	21st to end	Night	29% 15% 32% 20% 4	540
May	1st to 10th	Night	24% 13% 34% 24% 5%	540
	11th to 20th	Night	24% 12% 36% 23% 4	521
	21st to end	Night	23% 9% 29% 32% 7%	389
June	1st to 10th	Night	24% 11% 30% 28% 8%	360
	11th to 20th	Night	19% 5% 31% 34% 11%	360
	21st to end	Night	26% 4 30% 33% 7%	360
July	1st to 10th	Night	19% 5% 27% 37% 12%	350
	11th to 20th	Night	18% 3 29% 36% 13% 1	348
	21st to end	Night	16% 4 25% 42% 12% 1	394
August	1st to 10th	Night	16% 4 27% 39% 13%	510
	11th to 20th	Night	14% 6% 29% 36% 14% 1	532
	21st to end	Night	15% 8% 25% 36% 14% 1	666
September	1st to 10th	Night	15% 5% 33% 32% 14% 1	720
	11th to 20th	Night	19% 9% 28% 25% 16% 3	720
	21st to end	Night	19% 9% 30% 27% 14% 1	720
October	1st to 10th	Night	23% 9% 25% 29% 14% 1	720
	11th to 20th	Night	21% 12% 30% 26% 9% 1	720
	21st to end	Night	31% 13% 30% 20% 6%	792
November	1st to 10th	Night	23% 12% 31% 26% 6% 1	740
	11th to 20th	Night	24% 12% 35% 21% 8% 1	760
	21st to end	Night	25% 19% 30% 22% 5%	803
December	1st to 10th	Night	28% 13% 37% 17% 5%	850
	11th to 20th	Night	25% 19% 33% 19% 3	850
	21st to end	Night	29% 17% 33% 19% 2	859

Page generated at 2024-03-31 06:08:52. Version ac07

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