Maple Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Maple Ridge Observatory clear sky chart from 2005-11-06 to 2024-11-04.

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% 11% 4 8% 5% 5% 5% 4 5% 7% 33%	101322
	Night	14% 11% 4 9% 5% 5% 4 4 5% 6% 32%	97770
Transparency	Day	49% 6% 12% 21% 11% 1	104843
	Night	50% 7% 12% 20% 10% 1	102338
Seeing	Day	19% 16% 33% 21% 8% 3	15493
	Night	20% 13% 32% 25% 9% 1	24915

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	14% 18% 8% 13% 7% 5% 6% 3 4 5% 15%	2467
	11th to 20th	Day	14% 16% 6% 18% 11% 6% 4 4 4 4 13%	2530
	21st to end	Day	18% 22% 6% 13% 7% 6% 4 3 4 5% 11%	2814
February	1st to 10th	Day	11% 17% 6% 13% 9% 7% 6% 3 5% 5% 18%	1710
	11th to 20th	Day	11% 15% 6% 13% 8% 7% 5% 4 5% 5% 22%	1745
	21st to end	Day	11% 17% 6% 12% 8% 6% 5% 4 4 5% 22%	1570
March	1st to 10th	Day	13% 13% 3 9% 6% 5% 4 4 5% 5% 33%	3145
	11th to 20th	Day	10% 14% 7% 11% 5% 6% 4 3 6% 6% 27%	3480
	21st to end	Day	17% 12% 4 11% 6% 4 5% 4 6% 6% 26%	3815
April	1st to 10th	Day	18% 15% 4 8% 5% 4 4 3 4 6% 28%	2255
	11th to 20th	Day	18% 11% 3 7% 4 3 3 4 6% 5% 33%	2433
	21st to end	Day	17% 11% 3 7% 4 4 4 3 5% 6% 35%	2470
May	1st to 10th	Day	15% 9% 3 7% 5% 4 5% 4 5% 7% 37%	4108
	11th to 20th	Day	13% 7% 2 6% 4 5% 4 3 5% 7% 44%	4081
	21st to end	Day	12% 6% 2 5% 4 4 5% 4 5% 8% 47%	5047
June	1st to 10th	Day	13% 6% 3 5% 5% 5% 4 4 6% 8% 40%	2850
	11th to 20th	Day	12% 7% 2 6% 5% 4 5% 5% 6% 8% 41%	2850
	21st to end	Day	13% 6% 2 7% 5% 5% 5% 4 5% 7% 41%	2850
July	1st to 10th	Day	15% 7% 2 7% 5% 4 4 4 6% 7% 38%	4681
	11th to 20th	Day	8% 5% 2 5% 5% 5% 5% 5% 7% 10% 43%	4440
	21st to end	Day	9% 5% 2 5% 4 5% 4 4 7% 9% 46%	4793
August	1st to 10th	Day	10% 5% 2 6% 4 5% 6% 5% 7% 9% 42%	4104
	11th to 20th	Day	14% 6% 2 6% 4 4 4 4 6% 9% 43%	4044
	21st to end	Day	12% 7% 3 7% 5% 5% 5% 4 6% 7% 40%	4532
September	1st to 10th	Day	12% 7% 2 7% 4 5% 5% 4 6% 7% 42%	2196
	11th to 20th	Day	13% 5% 1 6% 4 4 4 4 6% 7% 45%	2090
	21st to end	Day	17% 8% 2 8% 5% 4 4 4 6% 7% 35%	2090
October	1st to 10th	Day	17% 9% 3 7% 5% 4 4 3 5% 7% 36%	2024
	11th to 20th	Day	20% 12% 4 9% 6% 4 5% 4 4 6% 25%	1884
	21st to end	Day	21% 17% 4 9% 6% 5% 4 5% 5% 5% 18%	1881
November	1st to 10th	Day	13% 15% 5% 8% 7% 6% 5% 4 6% 6% 27%	1699
	11th to 20th	Day	13% 14% 5% 12% 7% 6% 5% 4 5% 7% 21%	1630
	21st to end	Day	18% 19% 7% 10% 7% 5% 4 4 4 5% 18%	1520
December	1st to 10th	Day	13% 16% 8% 15% 8% 5% 5% 4 6% 5% 14%	1392
	11th to 20th	Day	15% 17% 6% 13% 8% 6% 5% 4 5% 5% 15%	1671
	21st to end	Day	23% 24% 10% 14% 5% 5% 4 3 2 3 7%	2431
January	1st to 10th	Night	15% 14% 6% 16% 7% 5% 5% 3 5% 5% 17%	4483
	11th to 20th	Night	12% 14% 6% 19% 9% 7% 6% 4 5% 5% 14%	4440
	21st to end	Night	13% 20% 8% 16% 8% 6% 5% 3 5% 4 13%	4852
February	1st to 10th	Night	10% 17% 5% 11% 8% 7% 5% 4 5% 6% 21%	2470
	11th to 20th	Night	12% 14% 5% 11% 8% 6% 5% 4 5% 6% 24%	2318
	21st to end	Night	16% 15% 5% 11% 6% 5% 5% 3 5% 5% 24%	1884
March	1st to 10th	Night	14% 10% 3 7% 4 4 4 3 5% 6% 40%	3692
	11th to 20th	Night	8% 12% 4 8% 5% 4 5% 3 5% 7% 38%	3479
	21st to end	Night	13% 11% 4 10% 6% 4 4 4 5% 6% 31%	3817
April	1st to 10th	Night	19% 12% 3 7% 4 4 5% 4 5% 6% 31%	1942
	11th to 20th	Night	18% 9% 3 6% 4 4 4 4 6% 6% 36%	1695
	21st to end	Night	17% 10% 3 8% 4 3 5% 4 4 7% 35%	1710
May	1st to 10th	Night	13% 8% 3 7% 5% 6% 6% 4 5% 6% 36%	2833
	11th to 20th	Night	12% 7% 3 6% 5% 5% 5% 4 7% 7% 40%	2812
	21st to end	Night	15% 6% 2 5% 4 4 4 4 5% 7% 44%	2533
June	1st to 10th	Night	13% 6% 2 6% 5% 5% 4 4 5% 8% 43%	1330
	11th to 20th	Night	9% 5% 2 6% 5% 4 5% 5% 8% 8% 42%	1330
	21st to end	Night	13% 6% 2 6% 4 4 4 4 5% 8% 44%	1330
July	1st to 10th	Night	10% 6% 2 6% 4 4 5% 4 6% 7% 46%	2271
	11th to 20th	Night	9% 5% 2 5% 4 4 4 4 5% 7% 50%	2530
	21st to end	Night	8% 5% 2 6% 4 3 4 4 6% 8% 50%	2769
August	1st to 10th	Night	9% 5% 2 6% 5% 4 5% 4 5% 8% 47%	2825
	11th to 20th	Night	15% 5% 2 4 3 3 3 3 5% 8% 49%	2785
	21st to end	Night	10% 5% 2 5% 4 4 4 3 5% 8% 50%	3124
September	1st to 10th	Night	11% 5% 2 5% 4 4 4 4 5% 7% 48%	1962
	11th to 20th	Night	12% 4 2 5% 3 4 3 4 5% 7% 50%	2090
	21st to end	Night	17% 7% 2 7% 3 4 5% 3 5% 7% 40%	2090
October	1st to 10th	Night	15% 7% 3 7% 4 4 4 3 4 7% 42%	2155
	11th to 20th	Night	18% 12% 3 8% 5% 4 4 3 5% 7% 30%	2294
	21st to end	Night	24% 13% 3 8% 5% 4 5% 3 4 5% 25%	2717
November	1st to 10th	Night	13% 13% 4 7% 6% 4 5% 4 5% 8% 32%	2452
	11th to 20th	Night	15% 15% 5% 9% 5% 6% 5% 5% 5% 7% 23%	2550
	21st to end	Night	19% 17% 5% 10% 6% 4 4 3 6% 6% 20%	2660
December	1st to 10th	Night	14% 16% 7% 11% 6% 5% 4 4 6% 6% 20%	2784
	11th to 20th	Night	14% 16% 7% 16% 8% 6% 5% 3 5% 6% 15%	3526
	21st to end	Night	23% 25% 9% 12% 5% 4 3 3 4 4 8%	5236

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	69% 9% 12% 9% 1	2468
	11th to 20th	Day	74% 7% 8% 10% 1	2530
	21st to end	Day	73% 7% 11% 6% 2	2814
February	1st to 10th	Day	65% 7% 10% 15% 4	1710
	11th to 20th	Day	62% 6% 11% 13% 8%	1754
	21st to end	Day	63% 6% 10% 15% 6% 1	1570
March	1st to 10th	Day	51% 6% 13% 20% 8% 1	3148
	11th to 20th	Day	54% 7% 13% 19% 6% 2	3480
	21st to end	Day	57% 6% 12% 16% 8% 1	3815
April	1st to 10th	Day	57% 5% 10% 18% 9% 1	2255
	11th to 20th	Day	50% 5% 10% 19% 15% 2	2433
	21st to end	Day	49% 5% 12% 16% 15% 3	2470
May	1st to 10th	Day	41% 8% 12% 20% 17% 2	4120
	11th to 20th	Day	38% 7% 15% 24% 14% 2	4085
	21st to end	Day	34% 7% 13% 19% 23% 5%	5047
June	1st to 10th	Day	39% 8% 12% 26% 13% 3	2850
	11th to 20th	Day	38% 7% 12% 24% 17% 2	2850
	21st to end	Day	41% 6% 12% 26% 13% 2	2850
July	1st to 10th	Day	45% 4 13% 22% 15% 1	4609
	11th to 20th	Day	33% 6% 13% 35% 12% 1	4365
	21st to end	Day	34% 6% 12% 25% 22% 1	4641
August	1st to 10th	Day	37% 5% 15% 29% 12% 1	4091
	11th to 20th	Day	38% 5% 16% 29% 12%	4083
	21st to end	Day	41% 6% 13% 29% 9% 1	4531
September	1st to 10th	Day	39% 7% 12% 28% 13% 1	2196
	11th to 20th	Day	36% 6% 14% 30% 13% 1	2090
	21st to end	Day	46% 6% 16% 23% 9%	2090
October	1st to 10th	Day	36% 5% 10% 32% 16% 1	3362
	11th to 20th	Day	54% 4 8% 20% 14%	3112
	21st to end	Day	62% 5% 9% 18% 6%	3081
November	1st to 10th	Day	56% 6% 11% 20% 7%	1699
	11th to 20th	Day	59% 8% 15% 13% 6%	1630
	21st to end	Day	67% 6% 15% 10% 2	1520
December	1st to 10th	Day	68% 9% 12% 8% 3	1392
	11th to 20th	Day	67% 8% 10% 12% 3	1671
	21st to end	Day	84% 5% 6% 4 1	2431
January	1st to 10th	Night	64% 9% 13% 11% 3	4483
	11th to 20th	Night	71% 9% 9% 10% 2	4440
	21st to end	Night	73% 7% 10% 7% 3	4852
February	1st to 10th	Night	63% 6% 11% 15% 6%	2470
	11th to 20th	Night	58% 8% 12% 16% 6%	2320
	21st to end	Night	59% 7% 12% 16% 7%	1884
March	1st to 10th	Night	44% 6% 16% 23% 10% 1	3702
	11th to 20th	Night	43% 6% 16% 24% 9% 1	3480
	21st to end	Night	50% 7% 13% 20% 8% 1	3817
April	1st to 10th	Night	52% 6% 10% 18% 13% 1	1942
	11th to 20th	Night	46% 4 8% 23% 15% 2	1695
	21st to end	Night	48% 7% 10% 17% 15% 3	1710
May	1st to 10th	Night	43% 10% 11% 19% 15% 2	2840
	11th to 20th	Night	36% 9% 11% 26% 16% 1	2813
	21st to end	Night	38% 8% 12% 19% 17% 6%	2534
June	1st to 10th	Night	38% 6% 12% 25% 17% 2	1330
	11th to 20th	Night	33% 8% 15% 24% 18% 2	1330
	21st to end	Night	38% 6% 12% 25% 15% 4	1330
July	1st to 10th	Night	36% 5% 16% 23% 17% 3	2235
	11th to 20th	Night	33% 5% 11% 35% 17% 1	2482
	21st to end	Night	32% 5% 16% 25% 21% 1	2681
August	1st to 10th	Night	36% 4 14% 29% 15% 1	2814
	11th to 20th	Night	34% 5% 17% 30% 13% 2	2812
	21st to end	Night	33% 5% 15% 34% 13% 1	3124
September	1st to 10th	Night	33% 8% 13% 29% 16% 2	1962
	11th to 20th	Night	32% 6% 16% 33% 12%	2090
	21st to end	Night	43% 7% 16% 23% 11%	2090
October	1st to 10th	Night	33% 5% 12% 34% 16%	3597
	11th to 20th	Night	48% 4 11% 24% 13%	3805
	21st to end	Night	54% 4 13% 23% 5%	4467
November	1st to 10th	Night	49% 7% 13% 23% 6% 1	2452
	11th to 20th	Night	58% 9% 13% 15% 6%	2550
	21st to end	Night	64% 8% 14% 11% 3	2660
December	1st to 10th	Night	63% 7% 14% 13% 3	2784
	11th to 20th	Night	68% 8% 11% 8% 4	3525
	21st to end	Night	79% 7% 7% 5% 3	5236

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	24% 17% 33% 20% 4	254
	11th to 20th	Day	23% 20% 39% 14% 4	270
	21st to end	Day	27% 17% 37% 14% 4 1	297
February	1st to 10th	Day	23% 25% 37% 13% 2	270
	11th to 20th	Day	21% 33% 34% 10% 1	270
	21st to end	Day	28% 33% 28% 10%	225
March	1st to 10th	Day	26% 27% 31% 13% 2 1	285
	11th to 20th	Day	23% 18% 37% 16% 5% 1	460
	21st to end	Day	30% 17% 33% 14% 6% 1	506
April	1st to 10th	Day	27% 20% 32% 17% 5% 1	460
	11th to 20th	Day	30% 18% 27% 15% 8% 2	452
	21st to end	Day	26% 18% 33% 15% 6% 2	460
May	1st to 10th	Day	21% 22% 32% 17% 6% 3	463
	11th to 20th	Day	17% 15% 37% 21% 7% 3	487
	21st to end	Day	13% 13% 36% 28% 6% 3	708
June	1st to 10th	Day	15% 16% 40% 21% 8% 1	680
	11th to 20th	Day	16% 15% 38% 23% 7% 2	680
	21st to end	Day	17% 12% 38% 25% 7% 2	680
July	1st to 10th	Day	11% 11% 33% 31% 12% 2	671
	11th to 20th	Day	11% 10% 35% 29% 10% 4	668
	21st to end	Day	11% 7% 34% 30% 13% 4	730
August	1st to 10th	Day	12% 10% 26% 29% 14% 7%	486
	11th to 20th	Day	10% 8% 24% 32% 16% 9%	479
	21st to end	Day	15% 11% 29% 26% 16% 3	539
September	1st to 10th	Day	14% 9% 36% 21% 13% 7%	490
	11th to 20th	Day	13% 9% 25% 31% 15% 7%	490
	21st to end	Day	22% 12% 25% 24% 13% 5%	490
October	1st to 10th	Day	24% 15% 28% 19% 13% 1	490
	11th to 20th	Day	26% 18% 33% 18% 4 1	474
	21st to end	Day	29% 26% 32% 9% 4	330
November	1st to 10th	Day	22% 20% 35% 16% 6%	279
	11th to 20th	Day	24% 27% 31% 13% 4	232
	21st to end	Day	31% 19% 34% 15% 1	180
December	1st to 10th	Day	26% 22% 33% 14% 3 1	180
	11th to 20th	Day	26% 27% 33% 11% 3	180
	21st to end	Day	31% 23% 31% 11% 4	198
January	1st to 10th	Night	21% 17% 38% 19% 4 1	950
	11th to 20th	Night	24% 17% 32% 20% 6%	950
	21st to end	Night	17% 13% 38% 25% 5% 1	1026
February	1st to 10th	Night	19% 19% 38% 19% 4	760
	11th to 20th	Night	20% 19% 34% 22% 5%	743
	21st to end	Night	25% 18% 36% 19% 3	628
March	1st to 10th	Night	17% 15% 39% 23% 6% 1	760
	11th to 20th	Night	20% 17% 35% 23% 5%	760
	21st to end	Night	20% 14% 33% 25% 7%	836
April	1st to 10th	Night	24% 14% 36% 20% 5% 1	612
	11th to 20th	Night	25% 11% 31% 24% 8% 1	563
	21st to end	Night	20% 13% 32% 25% 9% 1	570
May	1st to 10th	Night	16% 9% 35% 28% 10% 2	570
	11th to 20th	Night	19% 7% 29% 33% 11% 1	561
	21st to end	Night	12% 9% 28% 36% 14% 1	470
June	1st to 10th	Night	16% 7% 34% 32% 11%	380
	11th to 20th	Night	10% 8% 34% 34% 13% 1	380
	21st to end	Night	15% 8% 29% 34% 12% 1	380
July	1st to 10th	Night	7% 3 28% 44% 17%	404
	11th to 20th	Night	10% 3 25% 40% 20% 3	552
	21st to end	Night	9% 4 28% 37% 21% 1	624
August	1st to 10th	Night	10% 2 23% 41% 21% 2	567
	11th to 20th	Night	12% 4 21% 32% 26% 5%	564
	21st to end	Night	14% 6% 24% 34% 21% 1	627
September	1st to 10th	Night	12% 7% 27% 30% 19% 4	648
	11th to 20th	Night	14% 6% 25% 33% 18% 4	760
	21st to end	Night	21% 8% 25% 28% 15% 3	760
October	1st to 10th	Night	19% 10% 31% 27% 12% 1	760
	11th to 20th	Night	24% 14% 32% 24% 6%	760
	21st to end	Night	32% 14% 29% 20% 4 1	836
November	1st to 10th	Night	21% 16% 34% 21% 8% 1	755
	11th to 20th	Night	23% 19% 35% 18% 5%	760
	21st to end	Night	29% 14% 37% 17% 3	760
December	1st to 10th	Night	22% 20% 36% 17% 5%	884
	11th to 20th	Night	23% 20% 37% 15% 4 1	950
	21st to end	Night	27% 17% 35% 16% 4	1045

Page generated at 2024-11-01 22:47:48. Version ac07

Copyright © 2024 Attilla Danko.