Deer Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Deer Lake clear sky chart from 2005-11-06 to 2024-02-10.

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	21% 13% 5% 9% 8% 4 5% 5% 5% 6% 20%	77864
	Night	19% 13% 6% 11% 8% 4 6% 5% 5% 6% 18%	81140
Transparency	Day	66% 6% 10% 13% 5% 1	77562
	Night	69% 6% 9% 11% 4	80977
Seeing	Day	28% 17% 27% 19% 8% 2	16898
	Night	27% 15% 28% 23% 7% 1	24056

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	10% 14% 9% 15% 12% 8% 5% 6% 4 5% 12%	2437
	11th to 20th	Day	16% 12% 7% 24% 14% 6% 6% 4 3 3 5%	2530
	21st to end	Day	7% 12% 10% 15% 14% 7% 9% 7% 5% 3 11%	2783
February	1st to 10th	Day	16% 12% 6% 12% 16% 7% 8% 5% 5% 4 10%	1512
	11th to 20th	Day	16% 17% 8% 11% 11% 6% 6% 5% 5% 4 12%	1625
	21st to end	Day	12% 14% 6% 13% 10% 7% 9% 5% 6% 5% 14%	1480
March	1st to 10th	Day	15% 18% 7% 10% 9% 5% 5% 4 4 6% 16%	1796
	11th to 20th	Day	15% 18% 6% 10% 9% 6% 6% 4 4 6% 16%	1841
	21st to end	Day	17% 17% 8% 10% 9% 4 4 3 4 4 19%	2372
April	1st to 10th	Day	23% 18% 7% 10% 9% 4 4 4 4 4 13%	2160
	11th to 20th	Day	18% 15% 4 9% 6% 3 4 4 5% 6% 26%	2212
	21st to end	Day	22% 18% 6% 8% 5% 3 4 4 3 5% 22%	2358
May	1st to 10th	Day	24% 17% 4 7% 6% 2 3 4 3 5% 23%	2520
	11th to 20th	Day	22% 13% 4 6% 4 3 4 4 4 6% 30%	2478
	21st to end	Day	24% 13% 4 6% 5% 4 4 4 5% 7% 24%	2848
June	1st to 10th	Day	32% 10% 4 7% 5% 3 5% 4 4 6% 18%	2700
	11th to 20th	Day	24% 9% 3 6% 5% 3 5% 4 6% 7% 28%	2700
	21st to end	Day	25% 10% 4 7% 6% 3 4 5% 5% 6% 25%	2700
July	1st to 10th	Day	20% 9% 4 7% 6% 3 5% 6% 7% 7% 25%	2684
	11th to 20th	Day	17% 9% 4 6% 6% 4 6% 6% 6% 7% 30%	2520
	21st to end	Day	23% 7% 4 7% 7% 4 5% 5% 5% 7% 26%	2745
August	1st to 10th	Day	20% 7% 3 7% 7% 4 5% 6% 6% 8% 28%	2506
	11th to 20th	Day	22% 9% 4 6% 7% 4 5% 5% 5% 6% 28%	2402
	21st to end	Day	20% 8% 3 7% 6% 4 5% 5% 6% 7% 28%	2462
September	1st to 10th	Day	24% 8% 3 6% 5% 3 5% 4 5% 7% 30%	2160
	11th to 20th	Day	25% 9% 3 7% 7% 4 5% 5% 4 7% 24%	2052
	21st to end	Day	20% 10% 5% 8% 6% 4 3 5% 5% 7% 26%	1980
October	1st to 10th	Day	22% 11% 3 6% 5% 3 4 4 4 7% 31%	1894
	11th to 20th	Day	25% 14% 5% 8% 6% 3 5% 5% 5% 5% 21%	1665
	21st to end	Day	24% 15% 5% 10% 8% 3 4 4 3 5% 18%	1782
November	1st to 10th	Day	23% 19% 5% 11% 8% 5% 4 4 4 5% 11%	1670
	11th to 20th	Day	22% 17% 6% 11% 7% 3 6% 4 4 6% 14%	1520
	21st to end	Day	21% 17% 7% 14% 8% 5% 7% 4 4 4 10%	1330
December	1st to 10th	Day	21% 18% 8% 14% 9% 5% 6% 5% 4 5% 6%	1330
	11th to 20th	Day	30% 12% 7% 12% 10% 4 5% 4 4 4 7%	1668
	21st to end	Day	21% 17% 8% 15% 8% 3 4 4 4 5% 12%	2442
January	1st to 10th	Night	11% 14% 9% 14% 14% 6% 6% 5% 5% 5% 11%	4516
	11th to 20th	Night	14% 12% 7% 21% 10% 5% 6% 6% 5% 5% 8%	4440
	21st to end	Night	8% 11% 10% 17% 12% 6% 9% 5% 5% 4 14%	4884
February	1st to 10th	Night	15% 13% 6% 12% 16% 8% 6% 6% 5% 5% 8%	2653
	11th to 20th	Night	14% 16% 8% 13% 11% 6% 6% 5% 4 5% 11%	2217
	21st to end	Night	11% 13% 5% 11% 12% 6% 9% 5% 5% 5% 17%	1776
March	1st to 10th	Night	17% 16% 7% 9% 9% 6% 6% 5% 5% 6% 16%	2151
	11th to 20th	Night	13% 15% 6% 10% 8% 5% 7% 6% 5% 6% 19%	2117
	21st to end	Night	17% 17% 6% 10% 8% 3 5% 5% 4 5% 20%	1980
April	1st to 10th	Night	24% 16% 5% 9% 6% 4 5% 4 4 6% 17%	1800
	11th to 20th	Night	17% 13% 6% 8% 7% 4 5% 5% 5% 7% 22%	1698
	21st to end	Night	22% 15% 5% 8% 6% 3 5% 4 4 5% 23%	1601
May	1st to 10th	Night	22% 15% 5% 7% 5% 3 4 4 4 6% 24%	1440
	11th to 20th	Night	23% 13% 3 5% 4 3 4 4 4 6% 32%	1416
	21st to end	Night	27% 10% 2 5% 5% 3 5% 5% 6% 6% 27%	1422
June	1st to 10th	Night	30% 10% 4 8% 5% 4 4 4 4 7% 20%	1260
	11th to 20th	Night	21% 7% 3 5% 6% 3 5% 5% 7% 8% 31%	1260
	21st to end	Night	24% 10% 3 7% 6% 3 5% 5% 5% 8% 24%	1260
July	1st to 10th	Night	22% 6% 3 6% 5% 4 4 5% 7% 8% 30%	1271
	11th to 20th	Night	19% 8% 4 6% 5% 3 4 4 5% 8% 34%	1440
	21st to end	Night	24% 8% 4 6% 6% 4 4 4 6% 7% 28%	1573
August	1st to 10th	Night	18% 8% 3 8% 7% 3 6% 5% 7% 9% 27%	1433
	11th to 20th	Night	22% 7% 3 6% 6% 4 6% 5% 5% 6% 32%	1498
	21st to end	Night	16% 7% 3 6% 6% 3 6% 7% 6% 7% 31%	1893
September	1st to 10th	Night	21% 9% 3 5% 5% 3 5% 5% 5% 7% 33%	1800
	11th to 20th	Night	24% 9% 4 7% 5% 3 5% 5% 4 6% 27%	1907
	21st to end	Night	23% 9% 4 6% 6% 3 5% 5% 5% 7% 27%	1980
October	1st to 10th	Night	21% 9% 3 6% 6% 4 5% 4 6% 9% 27%	2064
	11th to 20th	Night	23% 11% 4 8% 6% 4 6% 4 5% 7% 22%	2294
	21st to end	Night	25% 13% 4 8% 6% 3 5% 4 4 6% 21%	2574
November	1st to 10th	Night	23% 15% 6% 9% 8% 5% 5% 6% 4 5% 15%	2408
	11th to 20th	Night	22% 16% 7% 9% 7% 4 5% 5% 5% 6% 13%	2658
	21st to end	Night	21% 16% 8% 13% 9% 4 4 4 4 5% 11%	2850
December	1st to 10th	Night	19% 20% 8% 13% 8% 5% 6% 5% 5% 5% 8%	2850
	11th to 20th	Night	28% 13% 7% 12% 9% 3 5% 5% 4 5% 8%	3531
	21st to end	Night	19% 16% 9% 16% 8% 4 5% 4 4 4 11%	5225

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	75% 7% 7% 7% 4	2438
	11th to 20th	Day	85% 6% 4 4 1	2530
	21st to end	Day	74% 8% 4 7% 4 3	2783
February	1st to 10th	Day	76% 7% 7% 6% 3 1	1512
	11th to 20th	Day	77% 7% 5% 7% 3	1633
	21st to end	Day	72% 7% 6% 10% 5% 1	1480
March	1st to 10th	Day	71% 5% 8% 10% 5% 1	1800
	11th to 20th	Day	70% 5% 7% 11% 6%	1841
	21st to end	Day	70% 5% 6% 9% 8% 1	2372
April	1st to 10th	Day	76% 5% 6% 8% 4 1	2160
	11th to 20th	Day	61% 5% 9% 16% 9% 1	2212
	21st to end	Day	67% 5% 7% 13% 7% 1	2358
May	1st to 10th	Day	66% 4 9% 15% 6%	2520
	11th to 20th	Day	58% 6% 9% 17% 10%	2482
	21st to end	Day	62% 5% 12% 14% 7%	2848
June	1st to 10th	Day	68% 5% 10% 12% 5%	2700
	11th to 20th	Day	56% 5% 12% 21% 5%	2700
	21st to end	Day	59% 7% 11% 14% 7% 1	2700
July	1st to 10th	Day	54% 9% 13% 19% 5%	2609
	11th to 20th	Day	51% 7% 13% 22% 7%	2444
	21st to end	Day	56% 7% 14% 18% 4	2592
August	1st to 10th	Day	51% 8% 17% 20% 5%	2492
	11th to 20th	Day	55% 8% 15% 16% 6% 1	2402
	21st to end	Day	55% 6% 16% 18% 5%	2462
September	1st to 10th	Day	52% 6% 12% 21% 8% 1	2160
	11th to 20th	Day	61% 6% 11% 16% 5% 1	2052
	21st to end	Day	57% 6% 16% 14% 7%	1980
October	1st to 10th	Day	54% 7% 13% 17% 7% 1	1894
	11th to 20th	Day	66% 5% 12% 13% 4	1665
	21st to end	Day	72% 5% 7% 12% 3 1	1782
November	1st to 10th	Day	78% 5% 9% 7% 1	1670
	11th to 20th	Day	72% 7% 7% 11% 3	1520
	21st to end	Day	77% 7% 8% 5% 3	1330
December	1st to 10th	Day	83% 6% 6% 4 1	1330
	11th to 20th	Day	83% 6% 5% 4 2	1667
	21st to end	Day	78% 6% 8% 6% 1	2442
January	1st to 10th	Night	77% 7% 5% 7% 4 1	4516
	11th to 20th	Night	79% 8% 5% 6% 2	4440
	21st to end	Night	74% 6% 5% 7% 7% 2	4884
February	1st to 10th	Night	80% 6% 6% 5% 2	2653
	11th to 20th	Night	78% 7% 7% 6% 2	2220
	21st to end	Night	71% 4 8% 10% 6%	1776
March	1st to 10th	Night	71% 6% 9% 9% 5%	2160
	11th to 20th	Night	66% 6% 8% 14% 5% 1	2118
	21st to end	Night	68% 5% 9% 10% 7% 1	1980
April	1st to 10th	Night	71% 5% 8% 9% 6% 1	1800
	11th to 20th	Night	63% 5% 9% 15% 8%	1698
	21st to end	Night	65% 6% 8% 12% 8%	1601
May	1st to 10th	Night	64% 5% 9% 15% 6% 1	1440
	11th to 20th	Night	57% 6% 10% 18% 9% 1	1417
	21st to end	Night	58% 7% 9% 20% 6%	1423
June	1st to 10th	Night	66% 6% 9% 14% 6%	1260
	11th to 20th	Night	52% 7% 16% 18% 6%	1260
	21st to end	Night	58% 8% 12% 14% 7%	1260
July	1st to 10th	Night	50% 8% 17% 19% 6%	1237
	11th to 20th	Night	49% 8% 14% 22% 6%	1392
	21st to end	Night	55% 7% 14% 22% 3	1486
August	1st to 10th	Night	52% 9% 17% 20% 2	1422
	11th to 20th	Night	52% 10% 16% 17% 5% 1	1498
	21st to end	Night	49% 9% 17% 20% 5%	1893
September	1st to 10th	Night	52% 7% 14% 21% 6%	1800
	11th to 20th	Night	59% 7% 12% 15% 7%	1907
	21st to end	Night	58% 5% 14% 17% 6%	1980
October	1st to 10th	Night	56% 7% 13% 15% 8% 1	2064
	11th to 20th	Night	63% 6% 13% 13% 3	2294
	21st to end	Night	68% 5% 9% 12% 5%	2574
November	1st to 10th	Night	72% 7% 9% 10% 2	2408
	11th to 20th	Night	74% 6% 9% 10% 2	2658
	21st to end	Night	78% 6% 7% 6% 3	2850
December	1st to 10th	Night	81% 7% 6% 6% 1	2850
	11th to 20th	Night	82% 5% 7% 4 1	3533
	21st to end	Night	79% 7% 6% 6% 1	5225

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	25% 21% 31% 14% 7% 1	370
	11th to 20th	Day	25% 21% 29% 18% 7% 1	370
	21st to end	Day	22% 20% 29% 23% 7%	407
February	1st to 10th	Day	27% 22% 27% 16% 6% 2	367
	11th to 20th	Day	25% 27% 26% 18% 3 1	336
	21st to end	Day	19% 22% 31% 17% 8% 3	280
March	1st to 10th	Day	24% 23% 29% 15% 6% 3	340
	11th to 20th	Day	27% 21% 24% 15% 10% 3	340
	21st to end	Day	28% 17% 30% 16% 7% 2	461
April	1st to 10th	Day	28% 28% 24% 14% 5%	420
	11th to 20th	Day	29% 19% 26% 18% 6% 2	490
	21st to end	Day	31% 17% 26% 18% 6% 2	600
May	1st to 10th	Day	37% 15% 20% 19% 6% 2	603
	11th to 20th	Day	29% 17% 23% 17% 12% 3	624
	21st to end	Day	32% 17% 26% 19% 5% 1	680
June	1st to 10th	Day	37% 10% 25% 18% 8% 2	630
	11th to 20th	Day	31% 10% 27% 21% 10% 1	630
	21st to end	Day	26% 12% 29% 20% 9% 5%	630
July	1st to 10th	Day	26% 12% 27% 21% 10% 4	620
	11th to 20th	Day	19% 12% 32% 24% 12% 1	618
	21st to end	Day	24% 12% 28% 25% 9% 2	685
August	1st to 10th	Day	21% 9% 26% 27% 14% 3	625
	11th to 20th	Day	23% 9% 30% 24% 11% 4	617
	21st to end	Day	21% 12% 27% 25% 11% 4	581
September	1st to 10th	Day	26% 14% 32% 18% 7% 3	450
	11th to 20th	Day	34% 16% 27% 14% 8% 1	396
	21st to end	Day	25% 19% 34% 16% 5% 1	360
October	1st to 10th	Day	22% 23% 31% 15% 8% 2	360
	11th to 20th	Day	32% 17% 20% 19% 9% 3	360
	21st to end	Day	34% 17% 23% 17% 8% 2	396
November	1st to 10th	Day	36% 20% 24% 15% 4 1	365
	11th to 20th	Day	31% 21% 23% 15% 8% 2	370
	21st to end	Day	34% 24% 24% 15% 3	370
December	1st to 10th	Day	29% 19% 31% 15% 6%	370
	11th to 20th	Day	29% 22% 28% 16% 4	370
	21st to end	Day	25% 20% 28% 16% 7% 2	407
January	1st to 10th	Night	26% 18% 31% 19% 6% 1	850
	11th to 20th	Night	21% 22% 33% 18% 5%	850
	21st to end	Night	22% 21% 29% 24% 4	935
February	1st to 10th	Night	23% 21% 30% 20% 5% 1	848
	11th to 20th	Night	25% 19% 32% 20% 4	711
	21st to end	Night	20% 14% 31% 21% 11% 2	592
March	1st to 10th	Night	23% 22% 30% 18% 5% 1	720
	11th to 20th	Night	20% 16% 28% 26% 9%	678
	21st to end	Night	27% 15% 30% 22% 7%	594
April	1st to 10th	Night	29% 19% 28% 19% 5%	540
	11th to 20th	Night	23% 13% 33% 24% 6% 1	534
	21st to end	Night	29% 12% 29% 23% 6%	540
May	1st to 10th	Night	30% 11% 26% 25% 8% 1	540
	11th to 20th	Night	30% 11% 23% 26% 10%	532
	21st to end	Night	32% 10% 28% 23% 7%	583
June	1st to 10th	Night	36% 8% 23% 24% 9% 1	540
	11th to 20th	Night	28% 6% 27% 29% 9%	540
	21st to end	Night	26% 9% 28% 26% 10% 1	540
July	1st to 10th	Night	24% 9% 31% 25% 10% 1	526
	11th to 20th	Night	19% 9% 30% 31% 10%	522
	21st to end	Night	25% 6% 27% 32% 9%	590
August	1st to 10th	Night	20% 7% 27% 33% 14% 1	538
	11th to 20th	Night	24% 6% 28% 29% 12% 1	532
	21st to end	Night	20% 7% 28% 30% 15% 1	594
September	1st to 10th	Night	24% 9% 32% 26% 8%	540
	11th to 20th	Night	31% 11% 26% 27% 4	540
	21st to end	Night	28% 12% 32% 21% 6%	540
October	1st to 10th	Night	26% 14% 28% 25% 6%	624
	11th to 20th	Night	29% 13% 25% 24% 8% 1	787
	21st to end	Night	33% 14% 25% 19% 8%	891
November	1st to 10th	Night	35% 19% 24% 18% 4	830
	11th to 20th	Night	33% 16% 25% 19% 7% 1	850
	21st to end	Night	32% 20% 27% 18% 3	850
December	1st to 10th	Night	30% 19% 25% 19% 6%	850
	11th to 20th	Night	30% 21% 29% 17% 3	850
	21st to end	Night	23% 19% 29% 21% 7% 1	935

Page generated at 2024-02-07 07:11:56. Version ac07

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