Meadville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Meadville 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% 12% 4 9% 5% 4 4 3 5% 7% 29%	101499
	Night	18% 13% 5% 9% 5% 4 4 3 4 6% 29%	98229
Transparency	Day	53% 6% 11% 19% 10% 1	105143
	Night	55% 5% 11% 18% 10% 1	102724
Seeing	Day	24% 17% 29% 19% 9% 3	14674
	Night	24% 15% 28% 23% 10% 1	24325

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	19% 24% 11% 14% 4 3 4 2 3 3 13%	2714
	11th to 20th	Day	14% 24% 8% 17% 8% 5% 2 2 3 4 13%	2840
	21st to end	Day	26% 20% 10% 17% 6% 4 3 2 2 3 8%	3124
February	1st to 10th	Day	17% 21% 6% 14% 9% 5% 3 2 3 4 17%	1710
	11th to 20th	Day	15% 17% 7% 16% 8% 4 3 4 4 4 17%	1663
	21st to end	Day	18% 19% 3 13% 5% 4 4 3 4 5% 22%	1537
March	1st to 10th	Day	22% 12% 6% 9% 4 3 4 4 5% 5% 25%	3435
	11th to 20th	Day	12% 19% 6% 10% 5% 4 4 2 5% 5% 29%	3480
	21st to end	Day	22% 12% 4 10% 4 3 3 2 4 5% 29%	3815
April	1st to 10th	Day	18% 15% 3 7% 5% 4 4 3 5% 7% 29%	2194
	11th to 20th	Day	21% 13% 3 6% 4 4 3 3 5% 5% 32%	2320
	21st to end	Day	21% 13% 3 7% 4 4 3 3 4 5% 33%	2470
May	1st to 10th	Day	23% 9% 3 8% 5% 4 4 4 5% 6% 30%	4082
	11th to 20th	Day	21% 9% 3 8% 4 4 4 4 6% 8% 29%	4103
	21st to end	Day	14% 5% 2 6% 5% 4 5% 4 6% 7% 41%	4823
June	1st to 10th	Day	17% 7% 2 7% 5% 5% 5% 3 6% 8% 35%	2660
	11th to 20th	Day	16% 6% 3 7% 5% 5% 5% 4 5% 8% 36%	2660
	21st to end	Day	17% 5% 2 5% 5% 5% 5% 4 6% 8% 37%	2660
July	1st to 10th	Day	11% 6% 2 6% 5% 5% 5% 5% 6% 10% 39%	4440
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 5% 6% 9% 41%	4129
	21st to end	Day	12% 6% 2 7% 5% 5% 6% 4 6% 8% 38%	4466
August	1st to 10th	Day	16% 8% 3 8% 6% 5% 5% 4 6% 8% 31%	4104
	11th to 20th	Day	16% 7% 3 8% 5% 5% 6% 5% 7% 9% 30%	4044
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 7% 8% 38%	4350
September	1st to 10th	Day	18% 7% 2 6% 3 4 4 3 5% 7% 39%	2280
	11th to 20th	Day	13% 6% 2 7% 4 4 5% 3 6% 8% 41%	2100
	21st to end	Day	21% 8% 4 7% 5% 4 4 3 6% 7% 32%	2088
October	1st to 10th	Day	18% 6% 3 7% 5% 5% 5% 5% 6% 7% 35%	1900
	11th to 20th	Day	23% 10% 3 8% 5% 3 4 4 4 6% 30%	1900
	21st to end	Day	26% 13% 3 7% 4 4 4 3 5% 6% 24%	2090
November	1st to 10th	Day	14% 13% 3 8% 6% 4 5% 4 5% 6% 33%	1833
	11th to 20th	Day	18% 20% 4 8% 4 4 4 3 4 6% 24%	1619
	21st to end	Day	20% 24% 6% 9% 5% 4 3 4 4 5% 16%	1600
December	1st to 10th	Day	20% 27% 10% 10% 6% 3 4 3 3 2 13%	1584
	11th to 20th	Day	19% 21% 8% 13% 5% 4 4 3 5% 5% 14%	1910
	21st to end	Day	28% 25% 8% 10% 5% 3 3 2 2 3 11%	2772
January	1st to 10th	Night	17% 25% 11% 16% 5% 3 3 2 3 3 11%	4228
	11th to 20th	Night	17% 20% 10% 18% 5% 5% 5% 3 3 3 10%	4120
	21st to end	Night	27% 21% 9% 15% 5% 3 2 2 2 3 11%	4532
February	1st to 10th	Night	19% 19% 5% 13% 7% 5% 4 2 3 4 19%	2470
	11th to 20th	Night	16% 17% 6% 15% 7% 5% 5% 3 4 4 17%	2403
	21st to end	Night	20% 14% 5% 16% 5% 4 4 3 4 4 22%	1910
March	1st to 10th	Night	23% 15% 4 8% 5% 3 2 3 4 5% 28%	3418
	11th to 20th	Night	18% 17% 8% 7% 4 3 3 2 4 5% 28%	3480
	21st to end	Night	19% 13% 4 9% 4 3 3 2 4 4 35%	3817
April	1st to 10th	Night	19% 16% 4 7% 5% 4 4 3 4 5% 29%	1984
	11th to 20th	Night	19% 11% 3 7% 4 4 5% 4 5% 6% 33%	1825
	21st to end	Night	15% 11% 3 6% 5% 4 5% 3 6% 7% 33%	1710
May	1st to 10th	Night	27% 9% 2 6% 5% 4 4 3 4 7% 31%	2813
	11th to 20th	Night	17% 9% 4 7% 4 4 4 3 5% 7% 35%	2787
	21st to end	Night	15% 5% 2 4 4 3 4 3 6% 10% 45%	2732
June	1st to 10th	Night	11% 6% 2 7% 6% 4 4 5% 8% 8% 40%	1520
	11th to 20th	Night	11% 5% 3 7% 6% 4 4 5% 5% 8% 42%	1520
	21st to end	Night	13% 6% 3 6% 4 4 4 4 6% 9% 40%	1520
July	1st to 10th	Night	14% 8% 3 7% 3 3 4 3 5% 8% 42%	2520
	11th to 20th	Night	13% 5% 2 5% 4 4 4 3 6% 9% 45%	2826
	21st to end	Night	10% 6% 2 6% 5% 4 5% 4 6% 8% 44%	3087
August	1st to 10th	Night	13% 8% 3 8% 5% 4 5% 4 5% 6% 39%	2825
	11th to 20th	Night	17% 7% 2 6% 4 4 4 4 6% 6% 39%	2785
	21st to end	Night	11% 4 2 6% 5% 5% 5% 4 7% 8% 43%	3272
September	1st to 10th	Night	14% 6% 2 6% 3 4 4 3 5% 6% 46%	1900
	11th to 20th	Night	12% 5% 2 5% 3 4 3 4 4 7% 50%	2076
	21st to end	Night	20% 7% 2 6% 5% 4 4 2 5% 6% 37%	2091
October	1st to 10th	Night	18% 6% 2 5% 4 4 4 4 5% 6% 42%	2280
	11th to 20th	Night	21% 8% 3 7% 4 4 5% 4 5% 6% 33%	2280
	21st to end	Night	25% 12% 3 7% 3 4 4 3 4 6% 29%	2508
November	1st to 10th	Night	15% 12% 3 6% 4 4 4 4 6% 7% 35%	2462
	11th to 20th	Night	20% 17% 4 8% 5% 4 4 3 6% 5% 24%	2780
	21st to end	Night	21% 22% 5% 8% 5% 3 4 3 5% 6% 20%	2800
December	1st to 10th	Night	20% 25% 9% 10% 5% 4 3 2 3 4 14%	2779
	11th to 20th	Night	18% 23% 8% 13% 5% 3 3 2 4 4 16%	3285
	21st to end	Night	26% 24% 8% 10% 5% 5% 4 3 3 4 9%	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	77% 3 7% 8% 4	2715
	11th to 20th	Day	77% 3 8% 10% 3	2840
	21st to end	Day	85% 3 6% 5% 1	3124
February	1st to 10th	Day	73% 3 7% 11% 5%	1710
	11th to 20th	Day	70% 5% 7% 12% 6%	1672
	21st to end	Day	65% 4 10% 14% 5% 2	1537
March	1st to 10th	Day	60% 5% 9% 23% 4	3435
	11th to 20th	Day	58% 5% 15% 16% 5% 1	3480
	21st to end	Day	57% 4 8% 19% 11% 1	3815
April	1st to 10th	Day	54% 6% 12% 16% 12% 1	2194
	11th to 20th	Day	53% 4 11% 18% 12% 2	2320
	21st to end	Day	54% 5% 9% 19% 11% 2	2470
May	1st to 10th	Day	54% 6% 8% 23% 8% 1	4120
	11th to 20th	Day	51% 8% 11% 21% 8% 1	4107
	21st to end	Day	40% 8% 12% 22% 14% 3	4837
June	1st to 10th	Day	46% 8% 11% 23% 11% 1	2660
	11th to 20th	Day	46% 7% 12% 20% 14% 1	2660
	21st to end	Day	43% 7% 11% 25% 13% 1	2660
July	1st to 10th	Day	39% 8% 13% 23% 15% 2	4370
	11th to 20th	Day	38% 7% 11% 26% 17% 1	4059
	21st to end	Day	41% 8% 13% 21% 16% 1	4324
August	1st to 10th	Day	49% 8% 12% 22% 8%	4091
	11th to 20th	Day	46% 9% 12% 25% 7% 1	4083
	21st to end	Day	39% 8% 13% 27% 12% 1	4350
September	1st to 10th	Day	44% 6% 12% 21% 14% 2	2280
	11th to 20th	Day	40% 8% 12% 24% 15% 1	2100
	21st to end	Day	51% 7% 11% 21% 11%	2088
October	1st to 10th	Day	37% 7% 14% 24% 17% 1	3160
	11th to 20th	Day	47% 6% 12% 19% 12% 4	3140
	21st to end	Day	46% 5% 14% 24% 11% 1	3428
November	1st to 10th	Day	50% 6% 11% 19% 13% 2	1833
	11th to 20th	Day	61% 5% 11% 14% 7% 2	1619
	21st to end	Day	70% 4 10% 11% 4 1	1600
December	1st to 10th	Day	77% 4 8% 9% 2	1584
	11th to 20th	Day	73% 5% 9% 11% 2	1906
	21st to end	Day	82% 3 7% 7% 1	2772
January	1st to 10th	Night	79% 3 8% 8% 3	4228
	11th to 20th	Night	79% 5% 7% 7% 2	4120
	21st to end	Night	81% 3 6% 8% 2	4532
February	1st to 10th	Night	70% 4 9% 12% 5%	2470
	11th to 20th	Night	69% 5% 8% 13% 5%	2405
	21st to end	Night	67% 4 8% 13% 8% 1	1910
March	1st to 10th	Night	59% 4 9% 22% 6%	3418
	11th to 20th	Night	58% 5% 14% 15% 7% 1	3480
	21st to end	Night	53% 3 8% 20% 14% 2	3817
April	1st to 10th	Night	56% 5% 10% 16% 11% 1	1984
	11th to 20th	Night	51% 5% 11% 18% 13% 2	1825
	21st to end	Night	48% 6% 12% 20% 10% 3	1710
May	1st to 10th	Night	54% 5% 9% 19% 10% 2	2840
	11th to 20th	Night	47% 9% 11% 22% 10% 2	2788
	21st to end	Night	34% 8% 14% 24% 16% 3	2739
June	1st to 10th	Night	39% 8% 12% 25% 15% 2	1520
	11th to 20th	Night	39% 7% 14% 23% 15% 2	1520
	21st to end	Night	39% 9% 14% 21% 17% 1	1520
July	1st to 10th	Night	42% 6% 11% 22% 18% 2	2480
	11th to 20th	Night	35% 7% 12% 29% 16% 2	2773
	21st to end	Night	37% 9% 12% 18% 24% 1	2988
August	1st to 10th	Night	45% 8% 10% 25% 11% 1	2814
	11th to 20th	Night	41% 8% 13% 30% 8%	2812
	21st to end	Night	36% 8% 15% 27% 12% 2	3272
September	1st to 10th	Night	36% 7% 13% 26% 16% 3	1900
	11th to 20th	Night	32% 6% 14% 25% 21% 1	2076
	21st to end	Night	47% 7% 11% 20% 14% 1	2091
October	1st to 10th	Night	38% 5% 10% 24% 22% 1	3800
	11th to 20th	Night	44% 6% 12% 18% 14% 5%	3779
	21st to end	Night	42% 4 15% 22% 16% 1	4120
November	1st to 10th	Night	47% 5% 13% 21% 12% 3	2462
	11th to 20th	Night	60% 5% 10% 15% 7% 3	2780
	21st to end	Night	65% 5% 11% 14% 3 1	2800
December	1st to 10th	Night	75% 4 9% 8% 3	2779
	11th to 20th	Night	72% 4 10% 11% 2	3288
	21st to end	Night	79% 4 9% 7% 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	34% 29% 26% 9% 3	237
	11th to 20th	Day	35% 31% 25% 6% 3	270
	21st to end	Day	31% 35% 27% 6% 1	297
February	1st to 10th	Day	34% 26% 34% 7%	270
	11th to 20th	Day	38% 27% 29% 6% 1	270
	21st to end	Day	42% 26% 26% 6%	235
March	1st to 10th	Day	33% 22% 30% 13% 2	460
	11th to 20th	Day	32% 22% 32% 10% 3 1	460
	21st to end	Day	37% 21% 26% 12% 3	506
April	1st to 10th	Day	29% 24% 28% 14% 4 1	460
	11th to 20th	Day	32% 21% 25% 13% 7% 2	452
	21st to end	Day	29% 20% 31% 15% 4 1	460
May	1st to 10th	Day	27% 21% 29% 16% 5% 2	463
	11th to 20th	Day	22% 17% 30% 20% 9% 1	487
	21st to end	Day	17% 11% 31% 24% 13% 4	529
June	1st to 10th	Day	19% 14% 31% 24% 9% 3	490
	11th to 20th	Day	20% 12% 27% 26% 13% 2	490
	21st to end	Day	19% 12% 35% 23% 9% 2	490
July	1st to 10th	Day	10% 9% 25% 31% 18% 7%	485
	11th to 20th	Day	14% 10% 28% 30% 13% 6%	484
	21st to end	Day	12% 9% 34% 26% 14% 5%	532
August	1st to 10th	Day	13% 8% 27% 28% 17% 7%	486
	11th to 20th	Day	16% 8% 27% 29% 11% 9%	479
	21st to end	Day	13% 9% 25% 29% 17% 6%	539
September	1st to 10th	Day	19% 10% 24% 25% 18% 5%	490
	11th to 20th	Day	11% 6% 25% 30% 20% 8%	490
	21st to end	Day	23% 13% 29% 18% 12% 4	490
October	1st to 10th	Day	20% 16% 27% 19% 15% 2	490
	11th to 20th	Day	27% 18% 32% 16% 6% 2	490
	21st to end	Day	36% 19% 28% 15% 2	539
November	1st to 10th	Day	27% 19% 33% 14% 6% 1	371
	11th to 20th	Day	36% 24% 26% 10% 3	209
	21st to end	Day	36% 23% 33% 9%	200
December	1st to 10th	Day	39% 27% 26% 4 3 1	196
	11th to 20th	Day	38% 23% 30% 7% 2	180
	21st to end	Day	32% 28% 33% 6% 1	198
January	1st to 10th	Night	31% 25% 32% 10% 2	760
	11th to 20th	Night	35% 23% 27% 14% 1	760
	21st to end	Night	26% 25% 33% 14% 2	836
February	1st to 10th	Night	33% 21% 30% 15% 1	760
	11th to 20th	Night	28% 24% 33% 13% 1	743
	21st to end	Night	31% 23% 31% 14% 1	628
March	1st to 10th	Night	27% 18% 35% 16% 3	760
	11th to 20th	Night	28% 20% 29% 19% 4 1	760
	21st to end	Night	28% 17% 31% 19% 5%	836
April	1st to 10th	Night	26% 20% 29% 19% 5%	760
	11th to 20th	Night	27% 14% 31% 21% 7% 1	701
	21st to end	Night	21% 13% 34% 28% 4 1	570
May	1st to 10th	Night	24% 10% 26% 30% 10% 1	570
	11th to 20th	Night	18% 11% 29% 33% 8% 1	549
	21st to end	Night	13% 7% 29% 30% 19% 2	411
June	1st to 10th	Night	12% 5% 34% 36% 13%	380
	11th to 20th	Night	12% 9% 24% 42% 13%	380
	21st to end	Night	12% 5% 31% 36% 15% 1	380
July	1st to 10th	Night	9% 5% 20% 43% 19% 4	370
	11th to 20th	Night	12% 4 22% 34% 24% 3	539
	21st to end	Night	13% 3 17% 42% 24% 1	624
August	1st to 10th	Night	12% 3 18% 39% 25% 3	567
	11th to 20th	Night	13% 4 17% 35% 28% 4	564
	21st to end	Night	15% 4 23% 29% 26% 3	710
September	1st to 10th	Night	16% 8% 20% 29% 24% 3	760
	11th to 20th	Night	13% 4 20% 34% 24% 4	760
	21st to end	Night	21% 11% 23% 26% 16% 4	760
October	1st to 10th	Night	19% 9% 27% 25% 17% 2	760
	11th to 20th	Night	24% 15% 29% 22% 8% 1	760
	21st to end	Night	32% 15% 31% 19% 3	836
November	1st to 10th	Night	21% 17% 28% 24% 8% 1	780
	11th to 20th	Night	31% 19% 30% 14% 5% 1	800
	21st to end	Night	33% 20% 29% 14% 4	800
December	1st to 10th	Night	35% 23% 27% 11% 3	795
	11th to 20th	Night	30% 27% 28% 13% 2	760
	21st to end	Night	34% 22% 31% 13% 1	836

Page generated at 2024-12-06 03:54:49. Version ac07

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