Economy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Economy clear sky chart from 2005-11-06 to 2024-01-16.

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	20% 10% 4 7% 6% 3 5% 4 5% 6% 30%	75220
	Night	21% 10% 4 7% 6% 3 5% 4 5% 6% 29%	74580
Transparency	Day	36% 38% 8% 12% 5%	74921
	Night	38% 38% 8% 11% 4	74414
Seeing	Day	25% 18% 31% 20% 6% 1	16235
	Night	25% 17% 31% 22% 5%	23638

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% 18% 7% 8% 6% 3 6% 4 5% 6% 21%	1516
	11th to 20th	Day	24% 14% 5% 8% 8% 3 5% 4 7% 5% 19%	1509
	21st to end	Day	14% 10% 5% 9% 8% 3 6% 5% 6% 8% 26%	1782
February	1st to 10th	Day	20% 12% 5% 9% 8% 5% 6% 4 4 6% 22%	1620
	11th to 20th	Day	18% 13% 5% 11% 7% 4 5% 5% 5% 5% 23%	1573
	21st to end	Day	12% 11% 5% 9% 8% 4 4 3 5% 8% 31%	1352
March	1st to 10th	Day	15% 12% 6% 10% 8% 4 5% 5% 5% 5% 25%	1958
	11th to 20th	Day	15% 10% 5% 9% 7% 5% 4 5% 5% 6% 29%	1980
	21st to end	Day	16% 14% 6% 8% 8% 3 4 4 3 5% 29%	2178
April	1st to 10th	Day	25% 12% 4 6% 6% 3 5% 4 4 6% 25%	2157
	11th to 20th	Day	20% 8% 3 7% 6% 4 4 4 5% 7% 31%	2204
	21st to end	Day	23% 10% 4 7% 6% 4 4 5% 4 7% 28%	2340
May	1st to 10th	Day	25% 11% 4 7% 6% 4 4 4 5% 6% 24%	2415
	11th to 20th	Day	22% 9% 3 6% 6% 3 4 4 5% 6% 33%	2478
	21st to end	Day	20% 9% 3 6% 6% 3 5% 4 6% 7% 29%	2724
June	1st to 10th	Day	25% 9% 4 7% 6% 3 5% 5% 4 7% 25%	2520
	11th to 20th	Day	22% 7% 3 6% 6% 3 5% 5% 5% 7% 32%	2677
	21st to end	Day	28% 7% 3 6% 5% 3 4 4 4 6% 28%	2700
July	1st to 10th	Day	18% 7% 2 5% 5% 3 5% 4 6% 7% 37%	2692
	11th to 20th	Day	17% 7% 4 5% 6% 3 4 5% 7% 9% 34%	2520
	21st to end	Day	21% 8% 4 7% 6% 3 5% 5% 6% 7% 30%	2696
August	1st to 10th	Day	15% 6% 2 5% 5% 3 5% 6% 7% 8% 37%	2327
	11th to 20th	Day	17% 8% 3 6% 5% 4 5% 5% 6% 8% 33%	2304
	21st to end	Day	15% 6% 3 6% 4 2 4 4 6% 8% 44%	2480
September	1st to 10th	Day	16% 6% 2 5% 4 3 5% 5% 5% 7% 41%	2160
	11th to 20th	Day	19% 7% 3 5% 5% 3 4 3 5% 6% 40%	2098
	21st to end	Day	20% 7% 2 5% 5% 2 3 4 5% 6% 42%	1918
October	1st to 10th	Day	17% 5% 3 7% 6% 3 4 4 5% 6% 39%	1800
	11th to 20th	Day	22% 9% 2 5% 5% 3 5% 6% 6% 6% 31%	1800
	21st to end	Day	21% 9% 4 7% 7% 3 4 4 5% 5% 30%	1980
November	1st to 10th	Day	23% 12% 3 6% 7% 3 4 4 4 5% 29%	1513
	11th to 20th	Day	22% 12% 5% 5% 5% 3 4 5% 4 6% 29%	1520
	21st to end	Day	19% 13% 6% 7% 7% 3 6% 4 5% 5% 25%	1520
December	1st to 10th	Day	25% 15% 5% 8% 6% 4 4 3 4 5% 23%	1520
	11th to 20th	Day	30% 14% 5% 7% 6% 3 3 4 3 4 21%	1906
	21st to end	Day	22% 14% 6% 12% 6% 3 5% 4 4 5% 19%	2783
January	1st to 10th	Night	19% 16% 6% 9% 8% 3 5% 5% 5% 5% 20%	2649
	11th to 20th	Night	22% 13% 6% 9% 5% 3 4 5% 5% 6% 21%	2569
	21st to end	Night	16% 10% 4 8% 7% 3 7% 5% 6% 9% 25%	2574
February	1st to 10th	Night	20% 12% 5% 10% 7% 4 6% 4 6% 6% 21%	2340
	11th to 20th	Night	18% 13% 5% 9% 7% 4 4 5% 5% 6% 24%	2273
	21st to end	Night	13% 12% 6% 8% 7% 3 5% 4 4 6% 30%	1902
March	1st to 10th	Night	15% 11% 5% 10% 7% 4 6% 5% 3 6% 28%	1987
	11th to 20th	Night	18% 9% 5% 7% 6% 4 5% 5% 6% 7% 29%	1979
	21st to end	Night	17% 11% 4 8% 6% 4 4 3 4 6% 33%	2178
April	1st to 10th	Night	25% 12% 3 7% 5% 3 4 5% 4 5% 26%	1802
	11th to 20th	Night	21% 9% 4 6% 6% 3 4 4 5% 7% 31%	1702
	21st to end	Night	26% 9% 4 6% 5% 3 3 4 4 6% 29%	1620
May	1st to 10th	Night	26% 12% 3 5% 6% 3 4 4 5% 5% 27%	1544
	11th to 20th	Night	25% 9% 3 5% 4 2 5% 4 5% 7% 32%	1416
	21st to end	Night	18% 9% 3 6% 6% 4 5% 4 6% 5% 33%	1550
June	1st to 10th	Night	27% 9% 3 6% 5% 3 4 4 5% 8% 27%	1440
	11th to 20th	Night	21% 7% 3 5% 5% 3 4 5% 5% 7% 35%	1295
	21st to end	Night	24% 9% 4 8% 6% 3 5% 5% 5% 6% 25%	1260
July	1st to 10th	Night	19% 8% 3 6% 5% 4 4 6% 6% 10% 29%	1260
	11th to 20th	Night	17% 6% 4 7% 6% 4 5% 5% 7% 8% 32%	1426
	21st to end	Night	20% 7% 3 7% 6% 4 6% 5% 6% 9% 27%	1618
August	1st to 10th	Night	16% 6% 3 5% 5% 4 4 5% 6% 7% 38%	1612
	11th to 20th	Night	19% 8% 3 6% 7% 3 5% 5% 7% 9% 28%	1596
	21st to end	Night	15% 6% 3 5% 5% 3 4 5% 6% 8% 40%	1875
September	1st to 10th	Night	15% 5% 3 6% 5% 3 5% 4 5% 7% 42%	1800
	11th to 20th	Night	19% 7% 2 4 5% 2 3 4 5% 6% 42%	1858
	21st to end	Night	20% 6% 2 5% 4 3 4 5% 5% 7% 39%	2041
October	1st to 10th	Night	18% 7% 2 5% 5% 3 5% 5% 5% 7% 38%	2160
	11th to 20th	Night	20% 8% 3 5% 4 3 5% 5% 5% 6% 35%	2160
	21st to end	Night	27% 9% 3 6% 5% 3 4 4 4 5% 30%	2376
November	1st to 10th	Night	24% 9% 3 6% 5% 3 5% 4 5% 6% 31%	2561
	11th to 20th	Night	22% 9% 3 7% 6% 3 4 5% 5% 7% 26%	2660
	21st to end	Night	22% 12% 5% 7% 6% 3 5% 5% 4 6% 26%	2660
December	1st to 10th	Night	26% 13% 5% 7% 6% 3 5% 4 5% 7% 21%	2660
	11th to 20th	Night	30% 14% 4 7% 5% 3 3 3 4 5% 23%	3293
	21st to end	Night	25% 13% 4 10% 6% 3 4 4 4 5% 22%	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	45% 42% 7% 5% 1	1517
	11th to 20th	Day	42% 44% 6% 7% 2	1509
	21st to end	Day	37% 40% 8% 10% 5%	1782
February	1st to 10th	Day	44% 37% 7% 7% 4	1620
	11th to 20th	Day	44% 39% 8% 7% 2	1581
	21st to end	Day	37% 37% 10% 10% 5% 1	1352
March	1st to 10th	Day	42% 38% 7% 9% 4	1962
	11th to 20th	Day	35% 38% 9% 12% 5% 1	1980
	21st to end	Day	39% 36% 7% 11% 5% 1	2178
April	1st to 10th	Day	40% 38% 5% 10% 6% 1	2157
	11th to 20th	Day	35% 36% 6% 12% 10% 1	2204
	21st to end	Day	36% 38% 7% 14% 5% 1	2340
May	1st to 10th	Day	40% 38% 7% 9% 5% 1	2415
	11th to 20th	Day	34% 39% 8% 14% 6%	2482
	21st to end	Day	33% 40% 9% 13% 5%	2724
June	1st to 10th	Day	41% 38% 9% 10% 2	2520
	11th to 20th	Day	34% 38% 9% 13% 5% 1	2677
	21st to end	Day	41% 39% 7% 9% 3 1	2700
July	1st to 10th	Day	30% 41% 10% 13% 6%	2617
	11th to 20th	Day	30% 40% 11% 12% 6%	2444
	21st to end	Day	34% 40% 9% 14% 3	2545
August	1st to 10th	Day	31% 40% 11% 13% 5%	2314
	11th to 20th	Day	31% 39% 11% 14% 5%	2304
	21st to end	Day	25% 38% 11% 19% 6%	2480
September	1st to 10th	Day	28% 39% 8% 16% 8% 1	2160
	11th to 20th	Day	29% 38% 9% 15% 9% 1	2098
	21st to end	Day	30% 38% 7% 17% 8%	1918
October	1st to 10th	Day	28% 39% 11% 18% 5%	1800
	11th to 20th	Day	34% 39% 10% 13% 3	1800
	21st to end	Day	37% 38% 8% 11% 5%	1980
November	1st to 10th	Day	34% 41% 7% 12% 6%	1513
	11th to 20th	Day	34% 41% 10% 11% 4	1520
	21st to end	Day	39% 42% 8% 8% 2	1520
December	1st to 10th	Day	42% 42% 8% 7% 1	1520
	11th to 20th	Day	50% 34% 7% 7% 1	1905
	21st to end	Day	54% 28% 11% 6% 1	2783
January	1st to 10th	Night	44% 41% 7% 6% 1	2649
	11th to 20th	Night	40% 43% 8% 7% 2	2569
	21st to end	Night	36% 41% 8% 10% 4 1	2574
February	1st to 10th	Night	43% 38% 6% 9% 4 1	2340
	11th to 20th	Night	41% 39% 9% 7% 3 1	2276
	21st to end	Night	40% 37% 8% 11% 4	1902
March	1st to 10th	Night	41% 38% 6% 10% 5%	1996
	11th to 20th	Night	36% 38% 9% 12% 5% 1	1980
	21st to end	Night	35% 37% 8% 12% 6% 1	2178
April	1st to 10th	Night	40% 37% 7% 8% 7% 1	1802
	11th to 20th	Night	35% 37% 5% 13% 9%	1702
	21st to end	Night	37% 36% 9% 9% 7% 1	1620
May	1st to 10th	Night	39% 38% 6% 10% 6%	1544
	11th to 20th	Night	34% 39% 8% 14% 5% 1	1417
	21st to end	Night	34% 38% 10% 13% 4	1551
June	1st to 10th	Night	39% 38% 8% 11% 3	1440
	11th to 20th	Night	34% 39% 7% 13% 7% 1	1295
	21st to end	Night	42% 38% 8% 8% 3	1260
July	1st to 10th	Night	32% 42% 12% 10% 4	1225
	11th to 20th	Night	32% 40% 9% 12% 6%	1379
	21st to end	Night	35% 41% 10% 9% 5%	1529
August	1st to 10th	Night	31% 38% 10% 16% 4	1600
	11th to 20th	Night	34% 40% 9% 13% 3	1596
	21st to end	Night	28% 39% 11% 17% 5%	1875
September	1st to 10th	Night	29% 39% 8% 17% 7%	1800
	11th to 20th	Night	29% 37% 9% 17% 8% 1	1858
	21st to end	Night	31% 38% 7% 16% 8% 1	2041
October	1st to 10th	Night	29% 39% 10% 16% 7%	2160
	11th to 20th	Night	32% 38% 9% 16% 4	2160
	21st to end	Night	39% 38% 6% 10% 6%	2376
November	1st to 10th	Night	33% 43% 8% 11% 5%	2561
	11th to 20th	Night	35% 43% 8% 10% 4	2660
	21st to end	Night	38% 42% 10% 9% 2	2660
December	1st to 10th	Night	40% 42% 9% 8% 1	2660
	11th to 20th	Night	50% 33% 6% 8% 3	3295
	21st to end	Night	52% 28% 10% 9% 2	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	27% 23% 31% 17% 1	370
	11th to 20th	Day	33% 23% 28% 12% 4	356
	21st to end	Day	22% 22% 37% 17% 2	374
February	1st to 10th	Day	29% 24% 31% 14% 2	340
	11th to 20th	Day	27% 32% 26% 13% 2	336
	21st to end	Day	20% 24% 35% 17% 3 1	280
March	1st to 10th	Day	20% 28% 35% 13% 3	412
	11th to 20th	Day	22% 26% 32% 14% 5%	420
	21st to end	Day	26% 25% 32% 12% 4	462
April	1st to 10th	Day	33% 29% 26% 11% 2	420
	11th to 20th	Day	24% 28% 30% 13% 5%	412
	21st to end	Day	28% 18% 32% 17% 6%	420
May	1st to 10th	Day	33% 19% 30% 12% 5% 1	498
	11th to 20th	Day	23% 17% 31% 21% 6% 1	624
	21st to end	Day	28% 15% 31% 22% 3 1	680
June	1st to 10th	Day	30% 13% 31% 19% 6%	630
	11th to 20th	Day	24% 16% 31% 24% 5% 1	630
	21st to end	Day	31% 10% 27% 24% 8% 1	630
July	1st to 10th	Day	23% 8% 34% 28% 7% 1	620
	11th to 20th	Day	21% 7% 31% 30% 11%	618
	21st to end	Day	23% 7% 31% 28% 9%	636
August	1st to 10th	Day	15% 6% 33% 36% 10% 1	446
	11th to 20th	Day	20% 11% 30% 28% 10% 2	439
	21st to end	Day	18% 10% 29% 29% 12% 2	495
September	1st to 10th	Day	16% 12% 33% 29% 9% 1	450
	11th to 20th	Day	24% 13% 30% 24% 8% 2	450
	21st to end	Day	19% 15% 35% 16% 13% 2	419
October	1st to 10th	Day	21% 13% 29% 23% 11% 3	360
	11th to 20th	Day	23% 21% 27% 19% 9% 1	360
	21st to end	Day	24% 23% 29% 16% 6% 1	396
November	1st to 10th	Day	28% 20% 30% 15% 6% 1	365
	11th to 20th	Day	29% 24% 28% 14% 4 1	370
	21st to end	Day	30% 24% 32% 11% 4	370
December	1st to 10th	Day	33% 21% 30% 14% 2 1	370
	11th to 20th	Day	34% 28% 26% 11% 1	370
	21st to end	Day	27% 27% 29% 14% 3	407
January	1st to 10th	Night	27% 24% 31% 16% 3	850
	11th to 20th	Night	28% 21% 31% 16% 4	815
	21st to end	Night	21% 24% 33% 18% 4	792
February	1st to 10th	Night	26% 23% 33% 16% 2	720
	11th to 20th	Night	26% 28% 30% 13% 2	703
	21st to end	Night	19% 21% 37% 20% 4 1	592
March	1st to 10th	Night	22% 22% 35% 18% 2	720
	11th to 20th	Night	22% 19% 32% 21% 6%	720
	21st to end	Night	22% 20% 32% 21% 5%	792
April	1st to 10th	Night	30% 18% 31% 19% 3	542
	11th to 20th	Night	26% 17% 32% 19% 5%	534
	21st to end	Night	29% 14% 31% 18% 6% 1	540
May	1st to 10th	Night	30% 13% 32% 19% 6%	540
	11th to 20th	Night	26% 14% 29% 26% 5%	532
	21st to end	Night	20% 15% 40% 22% 2	583
June	1st to 10th	Night	30% 11% 32% 23% 4	540
	11th to 20th	Night	24% 10% 32% 28% 6%	395
	21st to end	Night	27% 6% 29% 30% 8%	360
July	1st to 10th	Night	23% 5% 31% 35% 6%	350
	11th to 20th	Night	18% 9% 29% 35% 8%	509
	21st to end	Night	21% 6% 28% 36% 9%	590
August	1st to 10th	Night	16% 6% 29% 38% 10% 1	538
	11th to 20th	Night	20% 6% 30% 34% 9% 1	532
	21st to end	Night	18% 6% 27% 36% 12% 1	594
September	1st to 10th	Night	17% 9% 34% 31% 9% 1	540
	11th to 20th	Night	22% 11% 26% 31% 9% 1	598
	21st to end	Night	23% 12% 32% 24% 8% 1	720
October	1st to 10th	Night	23% 12% 26% 30% 8% 1	720
	11th to 20th	Night	24% 14% 35% 18% 8% 2	720
	21st to end	Night	32% 19% 26% 19% 4	792
November	1st to 10th	Night	27% 19% 28% 19% 6% 1	830
	11th to 20th	Night	25% 22% 29% 19% 4 1	850
	21st to end	Night	29% 24% 26% 18% 3	850
December	1st to 10th	Night	34% 18% 30% 16% 2	850
	11th to 20th	Night	33% 25% 29% 11% 2	850
	21st to end	Night	28% 25% 28% 16% 3 1	935

Page generated at 2024-01-13 10:37:55. Version ac07

Copyright 2024 Attilla Danko