Dover-Foxcroft
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dover-Foxcroft clear sky chart from 2005-11-06 to 2024-12-09.

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% 9% 3 7% 5% 4 4 4 5% 7% 34%	101507
	Night	18% 9% 3 7% 5% 4 4 4 5% 6% 35%	98281
Transparency	Day	48% 6% 12% 21% 12% 1	105018
	Night	47% 6% 13% 21% 12% 1	102847
Seeing	Day	25% 16% 30% 19% 7% 2	15754
	Night	23% 14% 31% 25% 7%	24131

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	15% 12% 3 7% 4 4 4 4 6% 7% 36%	2517
	11th to 20th	Day	16% 8% 3 9% 6% 5% 3 3 4 7% 36%	2520
	21st to end	Day	14% 10% 4 9% 6% 5% 5% 4 6% 5% 32%	2772
February	1st to 10th	Day	15% 13% 3 7% 6% 4 5% 4 5% 8% 30%	1686
	11th to 20th	Day	14% 11% 5% 10% 6% 5% 4 3 5% 5% 32%	1775
	21st to end	Day	15% 11% 4 8% 6% 6% 5% 4 5% 5% 32%	1570
March	1st to 10th	Day	24% 13% 3 6% 5% 4 3 3 4 5% 29%	3116
	11th to 20th	Day	20% 13% 3 8% 5% 3 4 3 4 5% 31%	3470
	21st to end	Day	25% 12% 3 6% 4 3 4 3 4 6% 30%	3838
April	1st to 10th	Day	23% 11% 3 7% 5% 4 4 3 4 6% 30%	2280
	11th to 20th	Day	19% 9% 3 6% 5% 4 5% 4 4 6% 35%	2408
	21st to end	Day	23% 11% 2 7% 4 4 4 3 4 6% 34%	2470
May	1st to 10th	Day	20% 9% 2 7% 5% 5% 5% 4 6% 6% 31%	4106
	11th to 20th	Day	21% 9% 2 7% 5% 5% 6% 4 6% 6% 30%	4144
	21st to end	Day	16% 6% 2 6% 5% 5% 5% 5% 7% 9% 33%	4992
June	1st to 10th	Day	24% 8% 3 7% 4 4 4 4 6% 8% 29%	2850
	11th to 20th	Day	18% 7% 2 7% 4 5% 4 4 5% 7% 36%	2850
	21st to end	Day	24% 8% 3 7% 5% 4 4 4 6% 6% 28%	2850
July	1st to 10th	Day	14% 5% 2 7% 5% 6% 5% 4 8% 9% 35%	4581
	11th to 20th	Day	15% 5% 2 6% 4 5% 5% 4 7% 8% 37%	4440
	21st to end	Day	17% 7% 3 6% 5% 4 4 4 5% 7% 37%	4814
August	1st to 10th	Day	17% 6% 3 7% 5% 5% 6% 4 6% 9% 32%	4117
	11th to 20th	Day	16% 8% 4 8% 5% 4 5% 4 6% 8% 32%	4045
	21st to end	Day	15% 6% 2 6% 4 4 4 4 6% 8% 41%	4482
September	1st to 10th	Day	11% 6% 2 6% 4 4 4 3 5% 8% 45%	2209
	11th to 20th	Day	15% 5% 2 5% 4 3 4 4 4 5% 50%	2090
	21st to end	Day	18% 5% 2 6% 4 4 4 4 4 8% 41%	2090
October	1st to 10th	Day	18% 7% 2 7% 5% 4 4 3 5% 8% 37%	2051
	11th to 20th	Day	20% 9% 2 7% 4 4 3 3 5% 6% 36%	1848
	21st to end	Day	23% 11% 4 7% 5% 4 4 3 5% 6% 30%	1881
November	1st to 10th	Day	17% 8% 2 8% 4 4 4 3 6% 7% 37%	1761
	11th to 20th	Day	19% 9% 2 5% 3 4 5% 4 5% 7% 37%	1765
	21st to end	Day	22% 8% 3 5% 4 3 4 3 5% 6% 37%	1600
December	1st to 10th	Day	22% 12% 4 9% 5% 4 4 2 4 6% 29%	1406
	11th to 20th	Day	22% 11% 2 5% 4 3 4 4 4 5% 36%	1668
	21st to end	Day	25% 10% 2 6% 5% 5% 4 3 5% 5% 31%	2445
January	1st to 10th	Night	13% 11% 4 9% 5% 5% 5% 4 5% 6% 34%	4429
	11th to 20th	Night	13% 10% 3 8% 6% 6% 5% 5% 6% 7% 30%	4440
	21st to end	Night	13% 11% 5% 10% 6% 6% 6% 4 5% 6% 29%	4884
February	1st to 10th	Night	14% 11% 4 9% 5% 5% 5% 4 6% 6% 30%	2493
	11th to 20th	Night	11% 11% 4 9% 7% 4 4 4 5% 6% 35%	2288
	21st to end	Night	15% 11% 3 8% 5% 5% 5% 4 5% 5% 34%	1884
March	1st to 10th	Night	27% 12% 3 6% 3 4 4 3 4 5% 30%	3724
	11th to 20th	Night	15% 11% 4 9% 6% 5% 6% 5% 6% 6% 27%	3489
	21st to end	Night	26% 11% 2 6% 4 4 5% 3 6% 7% 26%	3790
April	1st to 10th	Night	22% 12% 3 7% 5% 3 3 3 4 4 35%	1900
	11th to 20th	Night	20% 8% 3 6% 5% 5% 4 3 5% 6% 35%	1720
	21st to end	Night	25% 9% 4 5% 4 3 3 3 5% 5% 34%	1710
May	1st to 10th	Night	23% 8% 2 6% 4 4 4 4 5% 8% 32%	2834
	11th to 20th	Night	20% 9% 4 8% 6% 5% 5% 4 6% 7% 26%	2765
	21st to end	Night	16% 5% 2 7% 4 4 4 3 6% 9% 40%	2588
June	1st to 10th	Night	22% 9% 3 8% 4 5% 5% 3 5% 7% 30%	1330
	11th to 20th	Night	17% 7% 3 7% 4 5% 4 3 6% 8% 37%	1330
	21st to end	Night	24% 8% 3 6% 5% 4 4 4 5% 6% 31%	1330
July	1st to 10th	Night	12% 6% 2 7% 5% 6% 5% 5% 7% 9% 38%	2378
	11th to 20th	Night	18% 6% 2 7% 4 3 4 4 6% 9% 38%	2520
	21st to end	Night	15% 7% 2 5% 4 5% 4 3 6% 8% 41%	2739
August	1st to 10th	Night	21% 7% 3 7% 5% 5% 6% 4 5% 5% 32%	2780
	11th to 20th	Night	16% 10% 2 7% 5% 5% 5% 4 6% 7% 33%	2782
	21st to end	Night	13% 7% 2 5% 4 4 4 3 5% 7% 46%	3172
September	1st to 10th	Night	13% 5% 1 4 3 3 4 4 5% 7% 51%	1971
	11th to 20th	Night	15% 6% 2 5% 4 3 3 3 4 6% 50%	2090
	21st to end	Night	18% 7% 3 5% 4 3 3 3 4 6% 42%	2090
October	1st to 10th	Night	20% 6% 2 7% 3 3 4 3 6% 6% 40%	2128
	11th to 20th	Night	18% 7% 2 6% 5% 4 4 3 6% 6% 40%	2327
	21st to end	Night	24% 10% 2 6% 4 4 4 3 5% 5% 33%	2717
November	1st to 10th	Night	17% 9% 2 6% 4 5% 5% 3 5% 6% 37%	2537
	11th to 20th	Night	17% 7% 3 6% 5% 4 4 4 6% 7% 37%	2631
	21st to end	Night	19% 9% 3 7% 4 4 4 4 7% 7% 34%	2800
December	1st to 10th	Night	21% 12% 3 8% 5% 4 4 3 6% 5% 29%	2956
	11th to 20th	Night	22% 9% 3 6% 5% 5% 3 3 4 5% 35%	3531
	21st to end	Night	24% 11% 3 7% 3 3 3 2 4 4 34%	5204

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	45% 6% 16% 23% 9% 1	2518
	11th to 20th	Day	47% 4 12% 24% 11% 2	2520
	21st to end	Day	51% 6% 14% 16% 13% 1	2772
February	1st to 10th	Day	52% 5% 10% 18% 11% 3	1686
	11th to 20th	Day	53% 4 11% 17% 13% 1	1783
	21st to end	Day	52% 4 11% 18% 10% 5%	1570
March	1st to 10th	Day	59% 5% 8% 12% 13% 3	3119
	11th to 20th	Day	53% 6% 10% 16% 12% 2	3470
	21st to end	Day	55% 5% 5% 16% 16% 4	3838
April	1st to 10th	Day	55% 5% 9% 15% 12% 4	2280
	11th to 20th	Day	48% 6% 9% 21% 15% 1	2408
	21st to end	Day	53% 4 8% 18% 13% 4	2470
May	1st to 10th	Day	50% 8% 13% 17% 9% 2	4120
	11th to 20th	Day	52% 7% 14% 18% 8% 1	4148
	21st to end	Day	43% 10% 14% 18% 15% 1	4992
June	1st to 10th	Day	52% 7% 14% 19% 8% 1	2850
	11th to 20th	Day	46% 5% 12% 20% 15% 2	2850
	21st to end	Day	54% 7% 11% 17% 9% 1	2850
July	1st to 10th	Day	42% 7% 16% 22% 12% 1	4511
	11th to 20th	Day	41% 8% 15% 26% 10%	4365
	21st to end	Day	46% 6% 12% 25% 10% 1	4661
August	1st to 10th	Day	48% 7% 14% 25% 6%	4103
	11th to 20th	Day	48% 7% 16% 21% 8%	4084
	21st to end	Day	39% 6% 13% 25% 15% 1	4482
September	1st to 10th	Day	36% 7% 14% 26% 16% 1	2209
	11th to 20th	Day	35% 4 10% 31% 18% 2	2090
	21st to end	Day	41% 6% 10% 27% 14% 1	2090
October	1st to 10th	Day	54% 5% 10% 20% 11%	3402
	11th to 20th	Day	40% 3 14% 28% 13% 1	3051
	21st to end	Day	41% 4 17% 20% 18% 1	3081
November	1st to 10th	Day	46% 7% 15% 19% 13% 1	1761
	11th to 20th	Day	45% 6% 12% 20% 13% 3	1765
	21st to end	Day	47% 6% 16% 22% 9% 1	1600
December	1st to 10th	Day	56% 5% 11% 17% 10% 1	1406
	11th to 20th	Day	50% 4 12% 18% 14% 2	1668
	21st to end	Day	55% 5% 11% 18% 8% 3	2445
January	1st to 10th	Night	48% 6% 15% 21% 9% 1	4429
	11th to 20th	Night	48% 8% 15% 18% 9% 2	4440
	21st to end	Night	53% 6% 12% 17% 12% 1	4884
February	1st to 10th	Night	51% 8% 11% 18% 11% 2	2493
	11th to 20th	Night	48% 6% 11% 19% 15% 2	2291
	21st to end	Night	50% 6% 9% 19% 13% 4	1884
March	1st to 10th	Night	58% 5% 8% 17% 9% 3	3734
	11th to 20th	Night	52% 8% 15% 15% 9% 2	3490
	21st to end	Night	56% 5% 6% 18% 13% 2	3790
April	1st to 10th	Night	54% 4 7% 16% 16% 3	1900
	11th to 20th	Night	48% 6% 9% 21% 15% 2	1720
	21st to end	Night	52% 5% 10% 15% 14% 3	1710
May	1st to 10th	Night	48% 7% 18% 18% 8% 1	2840
	11th to 20th	Night	52% 9% 15% 16% 7% 1	2766
	21st to end	Night	41% 8% 16% 22% 13% 1	2589
June	1st to 10th	Night	52% 7% 12% 21% 8%	1330
	11th to 20th	Night	44% 8% 15% 20% 12% 2	1330
	21st to end	Night	53% 6% 13% 18% 9% 1	1330
July	1st to 10th	Night	40% 8% 18% 23% 12%	2338
	11th to 20th	Night	43% 7% 13% 28% 9%	2472
	21st to end	Night	40% 8% 15% 25% 12% 1	2651
August	1st to 10th	Night	53% 7% 11% 21% 7%	2770
	11th to 20th	Night	49% 7% 17% 18% 9%	2809
	21st to end	Night	37% 7% 14% 24% 17% 1	3172
September	1st to 10th	Night	33% 6% 14% 31% 15%	1971
	11th to 20th	Night	35% 6% 10% 29% 18% 1	2090
	21st to end	Night	42% 5% 10% 27% 15% 1	2090
October	1st to 10th	Night	45% 6% 12% 23% 13%	3544
	11th to 20th	Night	35% 4 13% 32% 16% 1	3863
	21st to end	Night	41% 4 14% 25% 14% 2	4467
November	1st to 10th	Night	45% 6% 13% 23% 12% 1	2537
	11th to 20th	Night	44% 6% 11% 22% 14% 2	2631
	21st to end	Night	47% 7% 15% 18% 11% 1	2800
December	1st to 10th	Night	54% 5% 12% 20% 9%	2956
	11th to 20th	Night	50% 5% 9% 19% 16% 1	3532
	21st to end	Night	53% 4 11% 19% 11% 2	5204

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	29% 21% 31% 16% 4	180
	11th to 20th	Day	35% 19% 32% 9% 2 2	180
	21st to end	Day	20% 20% 38% 19% 3	198
February	1st to 10th	Day	29% 18% 33% 17% 3	346
	11th to 20th	Day	26% 27% 33% 11% 3	420
	21st to end	Day	26% 24% 30% 17% 3	382
March	1st to 10th	Day	31% 22% 32% 13% 2	460
	11th to 20th	Day	27% 26% 30% 14% 3 1	460
	21st to end	Day	30% 23% 24% 15% 6% 2	506
April	1st to 10th	Day	36% 21% 26% 11% 5% 1	460
	11th to 20th	Day	33% 23% 27% 10% 6% 1	452
	21st to end	Day	32% 21% 28% 15% 3 2	460
May	1st to 10th	Day	33% 16% 30% 16% 5% 1	463
	11th to 20th	Day	25% 18% 32% 19% 4 1	487
	21st to end	Day	23% 18% 32% 21% 6%	619
June	1st to 10th	Day	28% 14% 30% 19% 9% 1	680
	11th to 20th	Day	24% 14% 27% 22% 11% 2	680
	21st to end	Day	28% 11% 27% 24% 9% 1	680
July	1st to 10th	Day	21% 10% 35% 22% 10% 2	574
	11th to 20th	Day	18% 10% 38% 22% 11% 2	484
	21st to end	Day	17% 9% 35% 27% 9% 3	532
August	1st to 10th	Day	17% 9% 34% 27% 10% 2	486
	11th to 20th	Day	18% 10% 28% 28% 12% 4	479
	21st to end	Day	19% 12% 29% 25% 12% 3	539
September	1st to 10th	Day	15% 13% 31% 25% 12% 3	490
	11th to 20th	Day	19% 12% 28% 21% 13% 7%	490
	21st to end	Day	19% 15% 27% 23% 10% 6%	490
October	1st to 10th	Day	20% 15% 26% 23% 14% 3	469
	11th to 20th	Day	27% 16% 31% 16% 8% 2	390
	21st to end	Day	32% 16% 28% 20% 4	429
November	1st to 10th	Day	27% 17% 26% 21% 8% 1	395
	11th to 20th	Day	31% 16% 34% 14% 6%	400
	21st to end	Day	32% 20% 24% 20% 5%	400
December	1st to 10th	Day	27% 17% 35% 16% 5%	216
	11th to 20th	Day	36% 23% 28% 10% 2 1	180
	21st to end	Day	33% 23% 25% 15% 5% 1	198
January	1st to 10th	Night	22% 19% 33% 23% 2	760
	11th to 20th	Night	25% 18% 32% 21% 3	760
	21st to end	Night	18% 20% 37% 21% 5%	836
February	1st to 10th	Night	22% 18% 34% 23% 3	760
	11th to 20th	Night	21% 24% 35% 17% 2	743
	21st to end	Night	26% 17% 31% 24% 2	628
March	1st to 10th	Night	26% 16% 36% 20% 2	760
	11th to 20th	Night	22% 19% 34% 20% 5%	760
	21st to end	Night	24% 19% 31% 21% 6%	836
April	1st to 10th	Night	30% 17% 32% 19% 2	760
	11th to 20th	Night	23% 17% 36% 18% 5%	596
	21st to end	Night	32% 15% 29% 20% 5%	570
May	1st to 10th	Night	27% 12% 32% 25% 4	570
	11th to 20th	Night	26% 11% 34% 22% 7%	540
	21st to end	Night	21% 8% 34% 31% 5% 1	411
June	1st to 10th	Night	23% 10% 30% 30% 6%	380
	11th to 20th	Night	19% 7% 31% 33% 9%	380
	21st to end	Night	29% 7% 25% 32% 8%	380
July	1st to 10th	Night	17% 4 33% 36% 10%	370
	11th to 20th	Night	19% 3 26% 40% 13%	368
	21st to end	Night	19% 4 24% 41% 12%	416
August	1st to 10th	Night	19% 7% 27% 32% 16%	535
	11th to 20th	Night	19% 6% 26% 35% 14% 1	562
	21st to end	Night	16% 6% 28% 36% 14% 1	649
September	1st to 10th	Night	15% 8% 28% 36% 12% 1	760
	11th to 20th	Night	20% 7% 26% 30% 16% 2	760
	21st to end	Night	20% 10% 30% 26% 13% 1	760
October	1st to 10th	Night	24% 7% 28% 29% 12%	760
	11th to 20th	Night	23% 13% 29% 24% 10% 1	760
	21st to end	Night	30% 14% 31% 21% 4	836
November	1st to 10th	Night	23% 14% 32% 23% 7%	780
	11th to 20th	Night	23% 15% 31% 23% 7% 1	816
	21st to end	Night	28% 15% 28% 24% 4	900
December	1st to 10th	Night	28% 12% 33% 20% 6%	893
	11th to 20th	Night	26% 18% 30% 22% 3	850
	21st to end	Night	30% 19% 30% 17% 4	926

Page generated at 2024-12-06 03:54:51. Version ac07

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