Carr's Mill Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carr's Mill Park clear sky chart from 2005-11-06 to 2024-11-06.

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	15% 6% 2 6% 4 4 4 4 6% 8% 41%	101268
	Night	15% 7% 2 6% 4 4 4 4 5% 7% 42%	97746
Transparency	Day	39% 6% 12% 24% 16% 3	104906
	Night	39% 5% 12% 24% 16% 3	102248
Seeing	Day	19% 11% 27% 24% 14% 5%	14975
	Night	18% 10% 29% 30% 12% 1	24431

By Month

Percentage Cloud Cover SE (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% 6% 2 5% 4 3 4 4 4 6% 46%	2545
	11th to 20th	Day	14% 11% 3 9% 5% 4 4 3 4 5% 38%	2840
	21st to end	Day	19% 9% 3 7% 5% 4 5% 3 4 6% 36%	3124
February	1st to 10th	Day	14% 8% 2 7% 6% 4 5% 4 7% 6% 39%	1710
	11th to 20th	Day	17% 8% 2 6% 4 4 4 4 5% 6% 40%	1718
	21st to end	Day	18% 8% 4 6% 5% 4 3 2 4 6% 39%	1570
March	1st to 10th	Day	22% 7% 2 5% 4 4 4 3 5% 7% 36%	3360
	11th to 20th	Day	10% 5% 2 5% 4 4 5% 4 6% 7% 48%	3480
	21st to end	Day	20% 7% 2 5% 4 4 4 3 4 6% 41%	3896
April	1st to 10th	Day	13% 8% 2 6% 5% 4 4 4 6% 8% 40%	2280
	11th to 20th	Day	13% 6% 3 7% 4 3 3 3 5% 6% 47%	2254
	21st to end	Day	18% 6% 3 5% 4 3 4 4 5% 6% 41%	2280
May	1st to 10th	Day	25% 7% 2 7% 4 4 5% 4 6% 8% 30%	4014
	11th to 20th	Day	23% 7% 3 7% 5% 5% 5% 4 6% 7% 29%	4329
	21st to end	Day	11% 4 2 6% 5% 4 4 4 6% 9% 45%	4823
June	1st to 10th	Day	11% 5% 2 6% 5% 4 5% 4 7% 10% 42%	2660
	11th to 20th	Day	11% 6% 2 6% 5% 5% 5% 5% 6% 8% 40%	2660
	21st to end	Day	10% 4 1 5% 4 4 5% 5% 7% 10% 45%	2660
July	1st to 10th	Day	6% 4 2 6% 5% 5% 6% 5% 8% 10% 43%	4440
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 5% 8% 11% 41%	4358
	21st to end	Day	11% 8% 2 7% 6% 5% 6% 5% 6% 8% 36%	4466
August	1st to 10th	Day	17% 6% 2 6% 4 5% 5% 5% 8% 8% 33%	4104
	11th to 20th	Day	11% 5% 2 6% 5% 5% 5% 4 7% 9% 40%	3867
	21st to end	Day	11% 5% 2 5% 4 4 5% 4 5% 8% 46%	4180
September	1st to 10th	Day	14% 6% 2 5% 4 4 4 4 5% 8% 46%	2280
	11th to 20th	Day	11% 5% 2 6% 4 4 4 3 6% 8% 47%	2280
	21st to end	Day	20% 7% 2 6% 4 3 5% 4 6% 6% 37%	2003
October	1st to 10th	Day	17% 5% 2 6% 4 3 3 3 5% 6% 45%	1900
	11th to 20th	Day	17% 5% 1 5% 3 3 3 4 5% 5% 48%	1900
	21st to end	Day	13% 5% 2 6% 4 4 4 3 5% 6% 48%	2090
November	1st to 10th	Day	12% 6% 2 4 3 3 3 3 6% 7% 51%	1788
	11th to 20th	Day	14% 5% 2 5% 3 4 3 4 5% 6% 49%	1687
	21st to end	Day	15% 6% 2 5% 4 4 3 3 5% 5% 47%	1520
December	1st to 10th	Day	17% 7% 2 6% 4 5% 4 4 7% 7% 39%	1520
	11th to 20th	Day	16% 6% 2 6% 4 4 4 3 5% 8% 42%	1910
	21st to end	Day	17% 7% 3 6% 4 4 5% 4 6% 8% 36%	2772
January	1st to 10th	Night	14% 8% 2 6% 4 4 4 3 5% 7% 42%	4397
	11th to 20th	Night	18% 8% 2 4 3 3 4 3 4 6% 44%	4120
	21st to end	Night	20% 9% 3 5% 3 3 3 3 5% 5% 40%	4532
February	1st to 10th	Night	14% 8% 2 6% 5% 4 4 4 5% 7% 41%	2470
	11th to 20th	Night	18% 7% 2 6% 4 4 3 3 4 6% 42%	2346
	21st to end	Night	16% 8% 2 7% 5% 4 3 3 5% 6% 41%	1884
March	1st to 10th	Night	20% 8% 3 6% 4 4 4 3 4 5% 39%	3491
	11th to 20th	Night	11% 5% 2 5% 3 4 5% 4 5% 7% 49%	3480
	21st to end	Night	14% 10% 3 6% 3 3 3 3 3 5% 47%	3734
April	1st to 10th	Night	15% 7% 3 5% 6% 4 4 4 5% 7% 40%	1900
	11th to 20th	Night	13% 6% 2 6% 4 3 5% 3 5% 7% 45%	1875
	21st to end	Night	16% 5% 2 5% 3 3 4 4 6% 7% 42%	1900
May	1st to 10th	Night	24% 9% 3 5% 4 4 4 3 6% 7% 31%	2908
	11th to 20th	Night	24% 9% 3 7% 4 4 4 4 5% 7% 30%	2562
	21st to end	Night	11% 5% 2 5% 4 4 5% 4 7% 10% 42%	2732
June	1st to 10th	Night	10% 5% 2 5% 4 4 4 5% 8% 9% 44%	1520
	11th to 20th	Night	11% 5% 2 8% 4 4 5% 4 6% 9% 41%	1520
	21st to end	Night	9% 5% 2 5% 5% 5% 5% 4 7% 10% 43%	1520
July	1st to 10th	Night	7% 5% 2 7% 6% 6% 6% 5% 7% 9% 40%	2520
	11th to 20th	Night	8% 6% 2 7% 5% 5% 6% 5% 8% 9% 39%	2584
	21st to end	Night	12% 7% 3 6% 4 5% 5% 4 7% 9% 38%	3087
August	1st to 10th	Night	18% 6% 2 7% 5% 4 5% 4 6% 9% 33%	2825
	11th to 20th	Night	10% 7% 3 9% 6% 5% 7% 4 6% 7% 37%	2930
	21st to end	Night	11% 5% 2 5% 4 4 4 4 5% 9% 47%	3476
September	1st to 10th	Night	15% 5% 2 6% 3 3 5% 3 4 7% 46%	1900
	11th to 20th	Night	10% 6% 3 6% 4 3 3 3 4 8% 52%	1900
	21st to end	Night	20% 6% 2 6% 4 4 4 3 4 6% 39%	2174
October	1st to 10th	Night	19% 6% 3 5% 3 4 3 3 4 5% 45%	2280
	11th to 20th	Night	15% 5% 1 5% 3 3 3 2 5% 6% 53%	2280
	21st to end	Night	15% 6% 1 4 3 3 4 3 5% 7% 49%	2508
November	1st to 10th	Night	12% 6% 1 5% 3 3 3 2 5% 6% 53%	2412
	11th to 20th	Night	13% 7% 2 5% 3 3 4 3 5% 5% 49%	2490
	21st to end	Night	13% 4 2 5% 5% 5% 4 3 6% 7% 47%	2660
December	1st to 10th	Night	16% 8% 3 6% 4 4 4 3 5% 7% 40%	2660
	11th to 20th	Night	17% 5% 2 6% 4 4 4 4 5% 6% 42%	3285
	21st to end	Night	15% 7% 2 6% 5% 5% 5% 4 6% 8% 36%	4884

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	38% 5% 9% 31% 13% 4	2546
	11th to 20th	Day	47% 5% 10% 21% 13% 4	2840
	21st to end	Day	51% 4 11% 22% 11% 2	3124
February	1st to 10th	Day	44% 5% 13% 25% 12% 2	1710
	11th to 20th	Day	44% 4 9% 26% 14% 3	1727
	21st to end	Day	47% 4 11% 20% 14% 4	1570
March	1st to 10th	Day	46% 6% 11% 22% 13% 2	3360
	11th to 20th	Day	32% 7% 9% 29% 19% 4	3480
	21st to end	Day	45% 4 10% 21% 17% 3	3896
April	1st to 10th	Day	40% 6% 12% 21% 16% 5%	2280
	11th to 20th	Day	38% 5% 10% 23% 19% 5%	2254
	21st to end	Day	42% 5% 10% 21% 18% 3	2280
May	1st to 10th	Day	52% 6% 11% 20% 10% 1	4051
	11th to 20th	Day	50% 9% 14% 18% 8% 1	4333
	21st to end	Day	34% 6% 15% 26% 16% 2	4837
June	1st to 10th	Day	37% 7% 14% 25% 15% 2	2660
	11th to 20th	Day	39% 9% 12% 24% 14% 2	2660
	21st to end	Day	32% 7% 16% 26% 18% 2	2660
July	1st to 10th	Day	34% 9% 17% 21% 13% 5%	4370
	11th to 20th	Day	35% 7% 16% 29% 11% 1	4283
	21st to end	Day	43% 8% 12% 20% 17% 1	4324
August	1st to 10th	Day	44% 9% 14% 25% 8%	4091
	11th to 20th	Day	37% 8% 13% 28% 14% 1	3906
	21st to end	Day	34% 6% 13% 27% 17% 2	4180
September	1st to 10th	Day	38% 5% 13% 21% 19% 4	2280
	11th to 20th	Day	35% 4 9% 27% 21% 4	2280
	21st to end	Day	46% 5% 8% 20% 19% 2	2003
October	1st to 10th	Day	38% 4 7% 18% 27% 5%	3160
	11th to 20th	Day	26% 5% 9% 26% 24% 10%	3140
	21st to end	Day	23% 3 10% 30% 29% 5%	3428
November	1st to 10th	Day	33% 4 13% 26% 20% 4	1788
	11th to 20th	Day	36% 4 10% 24% 23% 4	1687
	21st to end	Day	39% 4 11% 29% 16% 2	1520
December	1st to 10th	Day	43% 6% 13% 24% 12% 2	1520
	11th to 20th	Day	39% 6% 11% 31% 11% 2	1906
	21st to end	Day	45% 6% 15% 23% 11% 1	2772
January	1st to 10th	Night	40% 6% 10% 26% 14% 3	4397
	11th to 20th	Night	41% 4 12% 25% 16% 2	4120
	21st to end	Night	47% 4 7% 27% 14% 1	4532
February	1st to 10th	Night	42% 5% 13% 25% 13% 1	2470
	11th to 20th	Night	43% 3 9% 22% 18% 4	2348
	21st to end	Night	44% 4 9% 22% 15% 5%	1884
March	1st to 10th	Night	46% 5% 10% 26% 11% 2	3491
	11th to 20th	Night	32% 7% 10% 32% 16% 3	3480
	21st to end	Night	41% 4 8% 22% 20% 5%	3734
April	1st to 10th	Night	41% 6% 10% 20% 19% 4	1900
	11th to 20th	Night	39% 5% 11% 21% 18% 6%	1875
	21st to end	Night	38% 7% 10% 24% 15% 5%	1900
May	1st to 10th	Night	52% 5% 10% 19% 11% 2	2937
	11th to 20th	Night	51% 8% 12% 18% 10% 1	2563
	21st to end	Night	34% 8% 19% 25% 12% 2	2739
June	1st to 10th	Night	34% 7% 11% 28% 17% 2	1520
	11th to 20th	Night	38% 8% 13% 25% 14% 2	1520
	21st to end	Night	35% 6% 14% 25% 18% 3	1520
July	1st to 10th	Night	38% 8% 20% 17% 12% 4	2480
	11th to 20th	Night	37% 9% 17% 25% 11% 1	2536
	21st to end	Night	40% 7% 15% 20% 16% 1	2988
August	1st to 10th	Night	45% 8% 18% 21% 8% 1	2814
	11th to 20th	Night	42% 8% 11% 25% 12% 1	2957
	21st to end	Night	33% 6% 13% 30% 16% 2	3476
September	1st to 10th	Night	37% 6% 11% 21% 20% 5%	1900
	11th to 20th	Night	34% 3 10% 27% 23% 3	1900
	21st to end	Night	45% 5% 9% 19% 18% 3	2174
October	1st to 10th	Night	41% 5% 10% 20% 19% 5%	3800
	11th to 20th	Night	24% 4 10% 25% 30% 8%	3779
	21st to end	Night	23% 4 10% 32% 24% 6%	4120
November	1st to 10th	Night	33% 4 10% 27% 22% 5%	2412
	11th to 20th	Night	38% 4 8% 24% 21% 5%	2490
	21st to end	Night	37% 4 12% 26% 19% 3	2660
December	1st to 10th	Night	44% 5% 11% 25% 13% 2	2660
	11th to 20th	Night	42% 4 11% 22% 18% 3	3288
	21st to end	Night	43% 6% 16% 23% 11% 1	4884

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	30% 20% 30% 14% 4 1	187
	11th to 20th	Day	29% 23% 30% 14% 3	270
	21st to end	Day	26% 22% 35% 14% 3 1	297
February	1st to 10th	Day	24% 19% 42% 11% 3	270
	11th to 20th	Day	32% 20% 40% 6% 1	325
	21st to end	Day	32% 19% 30% 17% 3	382
March	1st to 10th	Day	22% 23% 30% 20% 4	460
	11th to 20th	Day	27% 19% 31% 18% 3 2	460
	21st to end	Day	24% 18% 33% 19% 5% 1	506
April	1st to 10th	Day	22% 17% 36% 17% 5% 2	460
	11th to 20th	Day	18% 17% 33% 16% 12% 4	452
	21st to end	Day	25% 12% 33% 20% 8% 2	460
May	1st to 10th	Day	26% 13% 28% 20% 8% 5%	463
	11th to 20th	Day	23% 10% 26% 25% 13% 3	487
	21st to end	Day	17% 5% 22% 27% 23% 6%	529
June	1st to 10th	Day	14% 9% 27% 25% 18% 8%	490
	11th to 20th	Day	16% 7% 24% 27% 20% 6%	490
	21st to end	Day	11% 4 26% 35% 18% 5%	490
July	1st to 10th	Day	12% 4 18% 32% 23% 12%	485
	11th to 20th	Day	6% 3 20% 32% 29% 11%	484
	21st to end	Day	12% 4 19% 32% 26% 7%	532
August	1st to 10th	Day	13% 2 18% 29% 27% 10%	486
	11th to 20th	Day	12% 4 17% 31% 25% 11%	479
	21st to end	Day	10% 4 19% 31% 22% 14%	539
September	1st to 10th	Day	16% 6% 19% 24% 21% 13%	490
	11th to 20th	Day	12% 4 20% 30% 22% 11%	490
	21st to end	Day	25% 10% 19% 29% 13% 4	490
October	1st to 10th	Day	21% 8% 22% 22% 20% 7%	490
	11th to 20th	Day	18% 12% 26% 27% 14% 3	490
	21st to end	Day	16% 10% 36% 26% 10% 2	539
November	1st to 10th	Day	16% 10% 32% 26% 13% 2	418
	11th to 20th	Day	20% 14% 32% 22% 11% 1	347
	21st to end	Day	25% 16% 34% 18% 7%	180
December	1st to 10th	Day	23% 16% 40% 14% 4 2	180
	11th to 20th	Day	27% 19% 29% 19% 6%	180
	21st to end	Day	26% 13% 36% 20% 6%	198
January	1st to 10th	Night	19% 19% 41% 19% 3	760
	11th to 20th	Night	23% 17% 33% 24% 4	760
	21st to end	Night	20% 17% 40% 21% 2	836
February	1st to 10th	Night	19% 15% 38% 25% 2	760
	11th to 20th	Night	25% 20% 37% 17% 1	743
	21st to end	Night	24% 17% 39% 16% 3	628
March	1st to 10th	Night	20% 16% 38% 23% 3	760
	11th to 20th	Night	21% 17% 34% 22% 5% 1	760
	21st to end	Night	19% 14% 40% 22% 4 1	836
April	1st to 10th	Night	21% 15% 38% 22% 4	760
	11th to 20th	Night	15% 13% 33% 30% 7% 1	751
	21st to end	Night	20% 9% 34% 28% 8% 1	760
May	1st to 10th	Night	21% 7% 29% 30% 12% 1	628
	11th to 20th	Night	21% 7% 28% 32% 11%	415
	21st to end	Night	15% 3 22% 37% 19% 3	411
June	1st to 10th	Night	12% 3 25% 37% 22% 1	380
	11th to 20th	Night	12% 4 20% 41% 21% 1	380
	21st to end	Night	11% 2 21% 48% 18% 1	380
July	1st to 10th	Night	8% 3 16% 43% 27% 3	370
	11th to 20th	Night	6% 1 13% 41% 35% 3	406
	21st to end	Night	9% 2 15% 44% 26% 4	624
August	1st to 10th	Night	12% 2 10% 42% 31% 3	567
	11th to 20th	Night	13% 4 13% 41% 26% 3	644
	21st to end	Night	12% 2 15% 39% 28% 5%	836
September	1st to 10th	Night	16% 3 18% 36% 25% 4	760
	11th to 20th	Night	12% 3 14% 38% 29% 4	760
	21st to end	Night	23% 5% 19% 33% 18% 2	760
October	1st to 10th	Night	21% 5% 20% 30% 19% 4	760
	11th to 20th	Night	17% 8% 27% 34% 13% 1	760
	21st to end	Night	19% 9% 31% 29% 12%	836
November	1st to 10th	Night	15% 7% 32% 34% 9% 2	764
	11th to 20th	Night	17% 16% 31% 29% 7% 1	760
	21st to end	Night	16% 15% 33% 28% 8%	760
December	1st to 10th	Night	22% 14% 35% 22% 7% 1	760
	11th to 20th	Night	17% 11% 44% 23% 5%	760
	21st to end	Night	20% 13% 38% 28% 2	836

Page generated at 2024-11-03 13:19:02. Version ac07

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