Milton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Milton clear sky chart from 2005-11-06 to 2024-11-12.

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	14% 6% 2 6% 4 4 4 4 6% 8% 42%	101240
	Night	15% 7% 2 6% 4 4 4 3 5% 7% 43%	97901
Transparency	Day	22% 47% 7% 13% 9% 2	104844
	Night	22% 47% 7% 13% 10% 2	102436
Seeing	Day	18% 13% 28% 25% 12% 4	15153
	Night	18% 11% 28% 30% 12% 1	24493

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	15% 7% 2 4 3 3 4 3 4 6% 50%	2517
	11th to 20th	Day	16% 8% 2 7% 5% 4 4 3 4 5% 42%	2689
	21st to end	Day	16% 10% 3 8% 5% 4 4 3 4 5% 37%	3124
February	1st to 10th	Day	14% 7% 3 7% 4 4 5% 4 7% 7% 40%	1710
	11th to 20th	Day	17% 6% 3 4 3 3 4 3 6% 6% 44%	1833
	21st to end	Day	17% 9% 3 7% 4 3 4 4 5% 5% 39%	1570
March	1st to 10th	Day	25% 7% 2 5% 3 3 3 3 4 7% 39%	3146
	11th to 20th	Day	10% 3 2 4 3 4 4 3 6% 8% 54%	3480
	21st to end	Day	19% 10% 2 5% 4 3 4 3 5% 6% 41%	4030
April	1st to 10th	Day	14% 8% 2 4 4 3 4 3 6% 7% 45%	2280
	11th to 20th	Day	11% 6% 2 5% 4 4 4 3 5% 8% 48%	2254
	21st to end	Day	15% 6% 2 6% 5% 4 3 3 6% 7% 43%	2280
May	1st to 10th	Day	20% 9% 3 8% 5% 5% 4 4 6% 8% 30%	3883
	11th to 20th	Day	26% 7% 3 6% 4 4 4 4 5% 7% 31%	4382
	21st to end	Day	10% 5% 2 6% 4 5% 5% 4 7% 9% 45%	4823
June	1st to 10th	Day	12% 6% 2 5% 4 5% 5% 4 7% 10% 41%	2660
	11th to 20th	Day	11% 5% 2 5% 4 5% 5% 4 6% 9% 43%	2660
	21st to end	Day	9% 4 2 5% 4 4 5% 5% 8% 10% 43%	2660
July	1st to 10th	Day	7% 4 2 6% 5% 5% 6% 5% 9% 11% 41%	4440
	11th to 20th	Day	11% 5% 2 7% 4 5% 6% 6% 8% 11% 37%	4440
	21st to end	Day	11% 5% 2 7% 6% 7% 7% 6% 8% 10% 31%	4606
August	1st to 10th	Day	15% 6% 2 6% 4 5% 6% 5% 9% 11% 32%	4050
	11th to 20th	Day	8% 4 3 7% 5% 6% 6% 5% 7% 8% 41%	3730
	21st to end	Day	10% 5% 2 6% 4 4 4 5% 6% 8% 47%	4180
September	1st to 10th	Day	14% 5% 2 5% 4 5% 5% 5% 6% 8% 42%	2280
	11th to 20th	Day	12% 6% 2 7% 4 4 4 3 5% 7% 47%	2251
	21st to end	Day	20% 7% 2 6% 5% 4 4 3 5% 7% 37%	2090
October	1st to 10th	Day	16% 5% 2 5% 4 5% 4 3 5% 6% 44%	1906
	11th to 20th	Day	17% 5% 2 4 2 3 3 2 4 5% 52%	1900
	21st to end	Day	14% 6% 2 5% 4 3 4 3 4 6% 49%	2060
November	1st to 10th	Day	13% 5% 2 4 4 3 3 3 5% 6% 52%	1761
	11th to 20th	Day	13% 7% 2 5% 4 4 4 3 4 6% 48%	1719
	21st to end	Day	15% 4 2 6% 4 3 3 3 5% 7% 48%	1644
December	1st to 10th	Day	16% 6% 2 5% 4 5% 5% 3 6% 7% 41%	1520
	11th to 20th	Day	15% 9% 3 6% 3 3 2 3 4 4 47%	1910
	21st to end	Day	15% 7% 2 5% 4 3 4 4 6% 7% 43%	2772
January	1st to 10th	Night	14% 8% 3 6% 3 4 4 3 5% 6% 45%	4429
	11th to 20th	Night	18% 7% 3 5% 4 3 3 2 4 5% 46%	4266
	21st to end	Night	19% 10% 3 5% 4 3 3 3 4 5% 41%	4532
February	1st to 10th	Night	17% 6% 2 6% 3 4 3 4 5% 6% 43%	2470
	11th to 20th	Night	17% 7% 2 6% 4 4 3 3 4 5% 43%	2232
	21st to end	Night	19% 6% 2 4 4 3 4 3 4 6% 45%	1884
March	1st to 10th	Night	21% 11% 3 6% 3 3 3 3 4 5% 37%	3702
	11th to 20th	Night	14% 5% 2 4 4 4 4 4 6% 7% 47%	3480
	21st to end	Night	17% 11% 3 6% 3 3 3 2 4 4 43%	3600
April	1st to 10th	Night	18% 7% 2 6% 4 4 4 3 5% 6% 42%	1900
	11th to 20th	Night	11% 6% 2 7% 5% 4 4 3 5% 6% 46%	1875
	21st to end	Night	17% 5% 2 6% 4 4 4 3 5% 8% 41%	1900
May	1st to 10th	Night	17% 10% 4 8% 5% 4 5% 4 5% 6% 32%	3011
	11th to 20th	Night	26% 8% 3 6% 5% 3 4 4 5% 6% 30%	2540
	21st to end	Night	11% 7% 2 7% 4 5% 5% 4 6% 8% 42%	2732
June	1st to 10th	Night	13% 7% 2 5% 4 4 5% 4 5% 8% 43%	1520
	11th to 20th	Night	10% 6% 2 6% 4 4 5% 4 6% 9% 42%	1520
	21st to end	Night	8% 5% 2 6% 5% 5% 4 5% 7% 11% 41%	1520
July	1st to 10th	Night	7% 5% 2 7% 5% 6% 5% 5% 7% 11% 39%	2520
	11th to 20th	Night	9% 6% 3 6% 5% 5% 5% 4 7% 10% 41%	2520
	21st to end	Night	12% 7% 3 9% 6% 5% 6% 4 6% 9% 33%	2943
August	1st to 10th	Night	16% 8% 3 7% 4 5% 4 4 6% 10% 33%	2847
	11th to 20th	Night	10% 5% 2 7% 5% 5% 5% 4 6% 9% 42%	3097
	21st to end	Night	8% 5% 2 5% 4 3 4 3 5% 8% 52%	3476
September	1st to 10th	Night	14% 6% 3 6% 4 4 4 3 6% 7% 45%	1900
	11th to 20th	Night	11% 5% 2 6% 3 3 4 3 6% 8% 49%	1928
	21st to end	Night	21% 6% 3 6% 4 4 4 4 5% 7% 37%	2090
October	1st to 10th	Night	17% 6% 2 6% 4 3 3 3 4 6% 46%	2270
	11th to 20th	Night	17% 4 2 4 4 3 3 2 3 6% 52%	2280
	21st to end	Night	15% 6% 2 5% 3 2 3 3 5% 6% 49%	2536
November	1st to 10th	Night	12% 5% 2 5% 3 3 4 3 4 5% 52%	2537
	11th to 20th	Night	15% 7% 2 6% 4 3 3 3 4 5% 48%	2484
	21st to end	Night	12% 6% 2 4 4 3 4 3 6% 6% 50%	2531
December	1st to 10th	Night	17% 9% 3 6% 4 3 3 3 5% 6% 42%	2660
	11th to 20th	Night	17% 6% 2 6% 4 4 4 3 4 6% 44%	3285
	21st to end	Night	14% 8% 3 7% 4 4 4 4 6% 7% 40%	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	23% 37% 5% 21% 12% 2	2518
	11th to 20th	Day	28% 38% 7% 13% 11% 4	2689
	21st to end	Day	32% 42% 7% 12% 6% 1	3124
February	1st to 10th	Day	16% 67% 5% 7% 4 1	1710
	11th to 20th	Day	16% 64% 3 9% 7% 2	1842
	21st to end	Day	17% 65% 5% 5% 6% 1	1570
March	1st to 10th	Day	33% 40% 4 13% 6% 3	3146
	11th to 20th	Day	13% 41% 7% 23% 14% 2	3480
	21st to end	Day	28% 41% 5% 10% 13% 4	4030
April	1st to 10th	Day	15% 65% 5% 7% 6% 1	2280
	11th to 20th	Day	13% 66% 4 9% 6% 1	2254
	21st to end	Day	14% 66% 5% 8% 6% 1	2280
May	1st to 10th	Day	37% 44% 6% 9% 3 1	3918
	11th to 20th	Day	35% 42% 8% 13% 2	4386
	21st to end	Day	19% 43% 9% 14% 14% 1	4837
June	1st to 10th	Day	14% 67% 5% 8% 6% 1	2660
	11th to 20th	Day	10% 68% 5% 10% 7% 1	2660
	21st to end	Day	10% 65% 6% 10% 8%	2660
July	1st to 10th	Day	23% 41% 16% 10% 8% 1	4370
	11th to 20th	Day	28% 38% 15% 15% 4	4365
	21st to end	Day	31% 38% 9% 12% 8% 1	4459
August	1st to 10th	Day	29% 39% 13% 16% 3	4037
	11th to 20th	Day	24% 40% 7% 23% 6%	3766
	21st to end	Day	18% 38% 8% 22% 13% 1	4180
September	1st to 10th	Day	15% 62% 7% 8% 6% 1	2280
	11th to 20th	Day	16% 61% 5% 9% 7% 2	2251
	21st to end	Day	23% 61% 3 9% 4 1	2090
October	1st to 10th	Day	18% 37% 5% 17% 18% 4	3166
	11th to 20th	Day	12% 36% 4 18% 22% 8%	3140
	21st to end	Day	10% 36% 8% 21% 18% 7%	3374
November	1st to 10th	Day	16% 56% 6% 12% 8% 3	1761
	11th to 20th	Day	15% 60% 3 9% 12% 2	1719
	21st to end	Day	14% 60% 3 15% 7% 1	1644
December	1st to 10th	Day	21% 60% 7% 6% 4 2	1520
	11th to 20th	Day	21% 47% 4 17% 7% 3	1906
	21st to end	Day	25% 39% 13% 13% 9%	2772
January	1st to 10th	Night	26% 37% 5% 18% 11% 3	4429
	11th to 20th	Night	27% 37% 7% 17% 12% 2	4266
	21st to end	Night	33% 39% 5% 15% 8% 1	4532
February	1st to 10th	Night	15% 66% 6% 9% 4 1	2470
	11th to 20th	Night	17% 64% 2 7% 9% 1	2234
	21st to end	Night	15% 64% 4 9% 6% 2	1884
March	1st to 10th	Night	36% 41% 5% 12% 5% 1	3702
	11th to 20th	Night	17% 41% 6% 19% 12% 3	3480
	21st to end	Night	29% 40% 4 10% 15% 3	3600
April	1st to 10th	Night	18% 65% 2 7% 7% 1	1900
	11th to 20th	Night	14% 66% 4 7% 7% 2	1875
	21st to end	Night	16% 65% 5% 6% 7% 1	1900
May	1st to 10th	Night	35% 44% 5% 13% 3	3041
	11th to 20th	Night	38% 42% 8% 11% 2	2541
	21st to end	Night	23% 42% 10% 11% 12% 2	2739
June	1st to 10th	Night	15% 66% 3 8% 8%	1520
	11th to 20th	Night	12% 66% 4 11% 7%	1520
	21st to end	Night	12% 65% 5% 10% 7% 1	1520
July	1st to 10th	Night	27% 41% 14% 11% 6% 1	2480
	11th to 20th	Night	26% 38% 16% 17% 3	2472
	21st to end	Night	35% 38% 10% 10% 8%	2849
August	1st to 10th	Night	35% 38% 11% 12% 4	2836
	11th to 20th	Night	24% 39% 9% 21% 7%	3127
	21st to end	Night	16% 37% 6% 21% 19% 1	3476
September	1st to 10th	Night	15% 61% 7% 11% 5% 2	1900
	11th to 20th	Night	14% 61% 5% 10% 10% 1	1928
	21st to end	Night	23% 61% 3 8% 5%	2090
October	1st to 10th	Night	22% 37% 7% 16% 16% 2	3790
	11th to 20th	Night	10% 37% 8% 13% 26% 5%	3779
	21st to end	Night	10% 36% 8% 21% 19% 6%	4172
November	1st to 10th	Night	18% 57% 4 11% 8% 3	2537
	11th to 20th	Night	16% 59% 3 8% 11% 3	2484
	21st to end	Night	13% 60% 4 13% 9% 1	2531
December	1st to 10th	Night	21% 60% 5% 9% 3 1	2660
	11th to 20th	Night	21% 49% 5% 11% 11% 2	3288
	21st to end	Night	27% 39% 12% 15% 6% 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	19% 25% 38% 14% 3 1	180
	11th to 20th	Day	24% 31% 28% 14% 3	229
	21st to end	Day	22% 25% 36% 13% 4	297
February	1st to 10th	Day	21% 26% 39% 11% 3	270
	11th to 20th	Day	28% 24% 36% 10% 3	441
	21st to end	Day	27% 21% 34% 13% 3	382
March	1st to 10th	Day	23% 25% 30% 17% 4	460
	11th to 20th	Day	23% 25% 33% 15% 3 2	460
	21st to end	Day	24% 19% 37% 15% 4 1	506
April	1st to 10th	Day	21% 24% 35% 14% 5% 2	460
	11th to 20th	Day	19% 15% 37% 23% 6% 1	452
	21st to end	Day	22% 16% 36% 19% 5% 2	460
May	1st to 10th	Day	24% 15% 32% 21% 7% 2	463
	11th to 20th	Day	22% 13% 32% 24% 9% 1	487
	21st to end	Day	17% 9% 22% 32% 15% 5%	529
June	1st to 10th	Day	16% 7% 27% 30% 16% 3	490
	11th to 20th	Day	12% 7% 28% 32% 16% 6%	490
	21st to end	Day	12% 7% 23% 35% 19% 4	490
July	1st to 10th	Day	11% 5% 19% 33% 25% 8%	485
	11th to 20th	Day	4 4 19% 39% 25% 9%	484
	21st to end	Day	10% 4 22% 35% 23% 6%	532
August	1st to 10th	Day	12% 3 22% 33% 22% 9%	486
	11th to 20th	Day	8% 4 17% 37% 26% 8%	479
	21st to end	Day	12% 4 19% 32% 21% 12%	539
September	1st to 10th	Day	16% 6% 21% 29% 15% 13%	490
	11th to 20th	Day	14% 4 23% 30% 20% 9%	490
	21st to end	Day	25% 9% 25% 26% 10% 4	490
October	1st to 10th	Day	21% 7% 26% 24% 14% 8%	490
	11th to 20th	Day	18% 12% 26% 25% 17% 2	490
	21st to end	Day	17% 11% 34% 24% 11% 3	522
November	1st to 10th	Day	15% 13% 31% 23% 15% 3	395
	11th to 20th	Day	17% 21% 30% 22% 9% 1	373
	21st to end	Day	17% 19% 32% 20% 10% 2	304
December	1st to 10th	Day	19% 23% 39% 13% 6%	180
	11th to 20th	Day	24% 25% 31% 15% 6%	180
	21st to end	Day	25% 19% 30% 21% 6% 1	198
January	1st to 10th	Night	19% 22% 34% 22% 4	760
	11th to 20th	Night	20% 17% 35% 23% 4	760
	21st to end	Night	20% 18% 38% 22% 3	836
February	1st to 10th	Night	20% 14% 38% 25% 3	760
	11th to 20th	Night	24% 22% 34% 19% 1	743
	21st to end	Night	22% 20% 35% 20% 3	628
March	1st to 10th	Night	20% 18% 35% 22% 5%	760
	11th to 20th	Night	23% 18% 34% 19% 6% 1	760
	21st to end	Night	22% 12% 37% 22% 5% 1	836
April	1st to 10th	Night	22% 14% 39% 19% 6%	760
	11th to 20th	Night	14% 13% 34% 32% 6%	751
	21st to end	Night	20% 10% 35% 28% 8%	760
May	1st to 10th	Night	20% 9% 33% 30% 7%	693
	11th to 20th	Night	20% 7% 31% 33% 9%	406
	21st to end	Night	16% 3 22% 42% 16% 2	411
June	1st to 10th	Night	16% 3 23% 43% 14% 1	380
	11th to 20th	Night	10% 2 22% 44% 21% 1	380
	21st to end	Night	9% 4 19% 53% 16%	380
July	1st to 10th	Night	10% 2 17% 48% 22% 1	370
	11th to 20th	Night	6% 4 12% 45% 32% 2	368
	21st to end	Night	5% 2 18% 45% 26% 3	532
August	1st to 10th	Night	10% 2 12% 45% 29% 3	576
	11th to 20th	Night	10% 3 15% 43% 26% 3	750
	21st to end	Night	11% 3 14% 39% 29% 4	836
September	1st to 10th	Night	18% 2 17% 34% 26% 4	760
	11th to 20th	Night	13% 3 15% 37% 27% 4	760
	21st to end	Night	24% 5% 20% 33% 17% 1	760
October	1st to 10th	Night	20% 6% 19% 32% 19% 4	760
	11th to 20th	Night	19% 8% 26% 31% 15% 1	760
	21st to end	Night	18% 7% 33% 27% 13% 2	836
November	1st to 10th	Night	13% 11% 33% 27% 13% 3	780
	11th to 20th	Night	19% 15% 29% 28% 8%	765
	21st to end	Night	14% 15% 31% 28% 11% 1	760
December	1st to 10th	Night	24% 14% 32% 20% 9% 1	760
	11th to 20th	Night	19% 16% 33% 26% 6%	760
	21st to end	Night	19% 13% 34% 31% 3	836

Page generated at 2024-11-08 22:45:36. Version ac07

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