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 2024-11-04.

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% 8% 2 6% 4 4 4 4 5% 7% 37%	101031
	Night	18% 8% 3 6% 4 4 4 4 5% 6% 37%	97961
Transparency	Day	45% 7% 12% 21% 13% 2	104556
	Night	45% 7% 12% 21% 13% 2	102526
Seeing	Day	23% 17% 31% 19% 8% 2	15315
	Night	23% 13% 32% 25% 7% 1	23949

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 6% 4 4 4 4 4 6% 41%	2517
	11th to 20th	Day	17% 7% 2 7% 4 4 4 3 5% 5% 42%	2520
	21st to end	Day	16% 12% 3 8% 4 3 4 3 5% 6% 36%	2772
February	1st to 10th	Day	17% 11% 3 6% 4 4 4 3 5% 6% 36%	1685
	11th to 20th	Day	12% 10% 4 9% 5% 4 5% 3 5% 6% 37%	1824
	21st to end	Day	16% 11% 3 7% 4 5% 4 4 6% 4 35%	1570
March	1st to 10th	Day	25% 13% 3 7% 4 4 4 3 4 5% 29%	3116
	11th to 20th	Day	17% 8% 3 7% 5% 5% 4 4 5% 6% 36%	3438
	21st to end	Day	24% 9% 3 7% 4 3 3 3 6% 6% 33%	3878
April	1st to 10th	Day	20% 11% 3 7% 4 3 4 3 4 6% 35%	2280
	11th to 20th	Day	18% 6% 2 5% 5% 4 4 4 6% 7% 38%	2371
	21st to end	Day	23% 8% 3 7% 4 4 4 3 5% 5% 34%	2470
May	1st to 10th	Day	24% 10% 3 7% 5% 4 5% 4 5% 6% 28%	4106
	11th to 20th	Day	18% 8% 2 7% 5% 6% 6% 4 5% 7% 31%	4134
	21st to end	Day	15% 6% 2 7% 4 5% 5% 4 7% 8% 37%	4837
June	1st to 10th	Day	22% 8% 3 5% 4 4 4 4 5% 8% 31%	2750
	11th to 20th	Day	18% 6% 2 6% 4 4 4 4 5% 8% 38%	2850
	21st to end	Day	24% 7% 2 6% 5% 5% 5% 4 6% 8% 29%	2734
July	1st to 10th	Day	14% 6% 2 7% 4 5% 6% 5% 7% 9% 36%	4440
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 5% 7% 10% 38%	4440
	21st to end	Day	19% 8% 2 6% 4 4 4 4 6% 7% 36%	4814
August	1st to 10th	Day	16% 6% 3 7% 5% 5% 5% 4 6% 8% 35%	4115
	11th to 20th	Day	16% 10% 3 8% 4 5% 5% 3 6% 7% 34%	4045
	21st to end	Day	10% 4 2 6% 4 4 4 4 6% 9% 46%	4387
September	1st to 10th	Day	12% 5% 2 5% 4 5% 4 3 6% 7% 48%	2223
	11th to 20th	Day	13% 5% 1 5% 2 3 3 3 5% 5% 54%	2090
	21st to end	Day	18% 5% 2 5% 4 3 3 3 5% 9% 44%	2090
October	1st to 10th	Day	18% 7% 2 6% 5% 4 4 3 4 6% 39%	2082
	11th to 20th	Day	19% 6% 2 6% 4 4 3 4 4 6% 41%	1834
	21st to end	Day	22% 8% 2 6% 4 4 4 3 4 6% 37%	1881
November	1st to 10th	Day	18% 6% 2 6% 3 3 5% 3 4 6% 44%	1698
	11th to 20th	Day	20% 6% 1 5% 4 3 4 4 5% 7% 42%	1710
	21st to end	Day	21% 8% 2 5% 3 2 3 2 4 6% 43%	1615
December	1st to 10th	Day	23% 11% 2 6% 4 4 4 3 4 6% 35%	1364
	11th to 20th	Day	23% 9% 2 5% 4 3 4 3 4 5% 38%	1668
	21st to end	Day	25% 12% 2 5% 4 4 4 3 5% 5% 30%	2683
January	1st to 10th	Night	14% 9% 3 7% 4 4 4 3 4 6% 40%	4429
	11th to 20th	Night	14% 10% 3 10% 5% 4 4 4 5% 7% 34%	4440
	21st to end	Night	18% 12% 3 8% 4 4 4 3 5% 6% 33%	4884
February	1st to 10th	Night	16% 9% 3 8% 5% 5% 5% 4 6% 6% 33%	2494
	11th to 20th	Night	12% 11% 3 6% 5% 5% 4 4 5% 6% 39%	2240
	21st to end	Night	15% 10% 3 7% 4 5% 4 3 4 6% 38%	1884
March	1st to 10th	Night	29% 11% 2 6% 4 4 3 3 3 5% 30%	3724
	11th to 20th	Night	14% 10% 3 9% 6% 4 5% 5% 5% 6% 32%	3521
	21st to end	Night	25% 11% 3 7% 4 4 4 4 6% 5% 29%	3739
April	1st to 10th	Night	21% 12% 3 5% 4 4 3 3 4 6% 35%	1900
	11th to 20th	Night	19% 7% 2 6% 5% 4 4 4 5% 6% 37%	1758
	21st to end	Night	23% 8% 3 6% 4 3 4 3 5% 5% 35%	1710
May	1st to 10th	Night	22% 9% 2 5% 4 4 4 4 6% 8% 30%	2834
	11th to 20th	Night	18% 8% 3 7% 5% 5% 6% 4 7% 8% 28%	2788
	21st to end	Night	17% 7% 2 6% 5% 4 5% 4 6% 7% 38%	2738
June	1st to 10th	Night	23% 7% 2 7% 6% 4 4 4 6% 6% 32%	1420
	11th to 20th	Night	16% 7% 2 6% 4 4 5% 4 5% 9% 38%	1330
	21st to end	Night	24% 9% 2 6% 4 2 4 4 7% 8% 30%	1436
July	1st to 10th	Night	13% 7% 2 7% 5% 6% 6% 5% 7% 9% 34%	2520
	11th to 20th	Night	14% 7% 2 6% 5% 5% 5% 4 6% 8% 37%	2520
	21st to end	Night	16% 6% 2 5% 4 4 5% 4 7% 8% 40%	2739
August	1st to 10th	Night	20% 7% 3 7% 5% 5% 5% 4 5% 6% 32%	2784
	11th to 20th	Night	16% 10% 3 7% 5% 4 5% 4 6% 9% 34%	2782
	21st to end	Night	10% 6% 2 6% 4 4 5% 4 6% 7% 45%	3252
September	1st to 10th	Night	13% 5% 2 5% 4 4 4 3 4 7% 49%	1956
	11th to 20th	Night	15% 6% 2 5% 2 2 3 3 4 6% 52%	2090
	21st to end	Night	16% 6% 2 5% 4 4 4 3 4 7% 45%	2090
October	1st to 10th	Night	18% 7% 3 5% 5% 3 4 4 5% 6% 40%	2097
	11th to 20th	Night	17% 6% 2 6% 4 5% 4 4 4 6% 42%	2343
	21st to end	Night	25% 8% 2 5% 3 4 4 3 4 6% 37%	2717
November	1st to 10th	Night	17% 6% 2 6% 3 4 4 3 5% 6% 44%	2453
	11th to 20th	Night	18% 6% 2 6% 4 4 4 4 4 6% 42%	2470
	21st to end	Night	17% 8% 2 5% 5% 4 4 4 5% 6% 40%	2561
December	1st to 10th	Night	22% 10% 2 7% 5% 4 4 3 5% 5% 33%	2816
	11th to 20th	Night	23% 8% 3 4 5% 4 4 2 4 5% 38%	3531
	21st to end	Night	25% 9% 3 6% 4 4 3 3 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	57% 5% 10% 11% 13% 3	3119
	11th to 20th	Day	44% 9% 11% 20% 13% 3	3438
	21st to end	Day	50% 6% 7% 15% 18% 4	3878
April	1st to 10th	Day	51% 5% 9% 16% 15% 4	2280
	11th to 20th	Day	43% 7% 11% 22% 14% 2	2371
	21st to end	Day	52% 6% 8% 17% 13% 4	2470
May	1st to 10th	Day	52% 11% 11% 16% 8% 1	4120
	11th to 20th	Day	47% 10% 16% 16% 9% 1	4138
	21st to end	Day	39% 11% 16% 19% 14% 1	4837
June	1st to 10th	Day	49% 9% 13% 20% 8%	2750
	11th to 20th	Day	44% 8% 12% 19% 15% 3	2850
	21st to end	Day	52% 8% 12% 17% 10% 1	2734
July	1st to 10th	Day	42% 8% 13% 25% 11%	4370
	11th to 20th	Day	38% 9% 16% 25% 10% 1	4365
	21st to end	Day	45% 8% 13% 20% 14% 1	4661
August	1st to 10th	Day	46% 9% 14% 24% 7%	4101
	11th to 20th	Day	48% 7% 16% 22% 7%	4084
	21st to end	Day	32% 8% 14% 26% 18% 1	4387
September	1st to 10th	Day	34% 7% 14% 26% 19% 1	2223
	11th to 20th	Day	32% 5% 10% 30% 21% 2	2090
	21st to end	Day	37% 7% 12% 27% 16% 1	2090
October	1st to 10th	Day	48% 7% 11% 21% 12% 1	3459
	11th to 20th	Day	35% 4 11% 29% 20% 1	3024
	21st to end	Day	36% 4 13% 24% 19% 3	3081
November	1st to 10th	Day	41% 6% 13% 23% 15% 2	1698
	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	57% 5% 9% 16% 10% 4	3734
	11th to 20th	Night	47% 10% 13% 19% 9% 2	3522
	21st to end	Night	53% 6% 7% 15% 16% 3	3739
April	1st to 10th	Night	50% 5% 9% 17% 15% 4	1900
	11th to 20th	Night	45% 6% 11% 21% 16% 1	1758
	21st to end	Night	50% 6% 12% 16% 13% 3	1710
May	1st to 10th	Night	48% 9% 16% 17% 8% 1	2840
	11th to 20th	Night	47% 13% 15% 17% 7% 2	2789
	21st to end	Night	42% 10% 17% 18% 12% 1	2739
June	1st to 10th	Night	51% 7% 12% 20% 9% 1	1420
	11th to 20th	Night	42% 8% 16% 19% 13% 2	1330
	21st to end	Night	49% 10% 14% 16% 8% 2	1436
July	1st to 10th	Night	43% 9% 15% 21% 11%	2480
	11th to 20th	Night	43% 8% 15% 24% 10%	2472
	21st to end	Night	39% 8% 15% 26% 12% 1	2651
August	1st to 10th	Night	52% 8% 14% 19% 7%	2774
	11th to 20th	Night	46% 9% 16% 20% 10%	2809
	21st to end	Night	34% 9% 15% 25% 16% 2	3252
September	1st to 10th	Night	35% 6% 14% 28% 16%	1956
	11th to 20th	Night	34% 5% 12% 29% 18% 2	2090
	21st to end	Night	38% 6% 11% 29% 14% 2	2090
October	1st to 10th	Night	43% 8% 14% 21% 14% 1	3500
	11th to 20th	Night	35% 5% 10% 28% 21% 1	3892
	21st to end	Night	38% 4 12% 27% 17% 2	4467
November	1st to 10th	Night	41% 6% 11% 25% 14% 1	2453
	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% 20% 30% 11% 5% 1	460
	11th to 20th	Day	27% 26% 27% 14% 4 2	452
	21st to end	Day	29% 22% 30% 13% 4 1	460
May	1st to 10th	Day	33% 17% 30% 15% 4 1	463
	11th to 20th	Day	21% 20% 36% 16% 6% 2	487
	21st to end	Day	21% 18% 38% 17% 6%	529
June	1st to 10th	Day	22% 15% 34% 19% 9% 1	580
	11th to 20th	Day	20% 15% 30% 21% 12% 2	680
	21st to end	Day	24% 13% 31% 21% 8% 2	564
July	1st to 10th	Day	17% 12% 38% 22% 8% 2	485
	11th to 20th	Day	13% 10% 40% 23% 10% 4	484
	21st to end	Day	16% 10% 38% 24% 10% 3	532
August	1st to 10th	Day	13% 8% 33% 31% 13% 1	486
	11th to 20th	Day	18% 10% 29% 26% 13% 4	479
	21st to end	Day	13% 13% 32% 26% 13% 4	539
September	1st to 10th	Day	16% 10% 32% 26% 13% 3	490
	11th to 20th	Day	18% 12% 29% 19% 14% 8%	490
	21st to end	Day	19% 15% 29% 22% 11% 5%	490
October	1st to 10th	Day	21% 15% 26% 22% 12% 3	485
	11th to 20th	Day	25% 13% 33% 17% 11% 2	390
	21st to end	Day	33% 13% 29% 19% 6% 1	429
November	1st to 10th	Day	25% 15% 30% 21% 8% 2	374
	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	760
	11th to 20th	Night	24% 16% 34% 22% 4	634
	21st to end	Night	28% 15% 33% 20% 4	570
May	1st to 10th	Night	24% 12% 33% 25% 5%	570
	11th to 20th	Night	23% 12% 35% 25% 5%	550
	21st to end	Night	22% 9% 30% 32% 7%	411
June	1st to 10th	Night	23% 10% 30% 29% 7%	380
	11th to 20th	Night	18% 6% 31% 34% 11%	380
	21st to end	Night	26% 5% 30% 32% 7%	380
July	1st to 10th	Night	19% 5% 27% 38% 12%	370
	11th to 20th	Night	18% 4 29% 36% 13% 1	368
	21st to end	Night	16% 4 24% 43% 12% 1	416
August	1st to 10th	Night	17% 4 27% 38% 12%	539
	11th to 20th	Night	15% 6% 29% 36% 14% 1	562
	21st to end	Night	15% 8% 26% 36% 15% 1	703
September	1st to 10th	Night	14% 6% 33% 32% 14% 1	760
	11th to 20th	Night	18% 8% 27% 25% 18% 3	760
	21st to end	Night	19% 9% 29% 27% 14% 1	760
October	1st to 10th	Night	22% 9% 25% 29% 14% 1	760
	11th to 20th	Night	21% 12% 31% 26% 9% 1	760
	21st to end	Night	30% 13% 30% 21% 6%	836
November	1st to 10th	Night	23% 12% 31% 26% 6% 1	755
	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 2024-11-01 22:47:29. Version ac07

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